In the following item, a descriptive passage about the dinosaur Iguanodon is jumbled. The passage consists of six sentences with S1 and S6 fixed. The four middle sentences labelled P, Q, R and S are given in random order. Read the sentences describing the size, teeth and limbs of Iguanodon and choose the option that gives the correct sequence of P, Q, R and S between S1 and S6. S1: Iguanodon was one of the first dinosaurs to be scientifically described. S6: This quadrupedal dinosaur lived about seventy million years ago and its fossils are found in many parts of England, Europe, Asia and North Africa. P: These teeth formed a dental battery in which replacing teeth were constantly growing. Q: The forelimbs were slightly larger than those of other members of its group known as Ornithischia. R: It had numerous teeth in the sides of the jaws, arranged in rows. S: It was about forty feet in length. The proper sequence should be

Introduction / Context:
This jumbled passage provides factual information about the dinosaur Iguanodon. It begins by stating that Iguanodon was one of the first dinosaurs to be scientifically described and ends with information about its age and fossil distribution. The middle sentences must describe its size, teeth and limbs in a logical order that would typically be used in a scientific description.

Given Data / Assumptions:

• S1: Introduces Iguanodon as an early scientifically described dinosaur.
• S6: Indicates that it lived about seventy million years ago and where its fossils are found.
• S: States that it was about forty feet long.
• R: Says that it had numerous teeth in the sides of the jaws arranged in rows.
• P: Explains that these teeth formed a dental battery with constantly replacing teeth.
• Q: States that the forelimbs were slightly larger than those of other members of its group Ornithischia.
• We assume the passage will move from general physical description (size), to dental features, to limb description, before concluding with time and fossil information in S6.

Concept / Approach:
Scientific descriptions often follow a structured pattern:

• Overall size or length of the organism.
• Key anatomical features such as teeth and skull.
• Additional physical details such as limbs and posture.

We must also ensure pronouns like “these teeth” in P refer back correctly to a previous sentence that has already introduced the teeth in R.

Step-by-Step Solution:
Step 1: After S1, which introduces the dinosaur, S is the best candidate because it gives an immediate impression of size: “It was about forty feet in length.” Size is usually one of the first physical details in such descriptions. Step 2: Once size has been described, the passage can focus on specific anatomical features. Sentence R tells us that Iguanodon had numerous teeth in the sides of its jaws arranged in rows. This is logically the next level of detail after size. Step 3: Sentence P begins with “These teeth”, which must refer to teeth mentioned in the immediately preceding sentence. Therefore P must follow R. It explains how the teeth formed a dental battery with constantly replacing teeth. Step 4: Once the teeth have been fully described, further physical detail is provided by Q, which states that the forelimbs were slightly larger than those of other members of Ornithischia. Limb size comes naturally after describing size and teeth. Step 5: The resulting sequence S R P Q gives a consistent and well organised description between S1 and S6.

Verification / Alternative check:
Reading the full passage with S, R, P and Q in that order, we get a smooth flow: introduction of the dinosaur, its length, details of its teeth, special features of those teeth, and a final note about its forelimbs, followed by age and fossil distribution. The pronoun “These teeth” clearly refers back to teeth introduced immediately before, and all the information is presented in a logical descriptive order, confirming that the sequence is correct.

Why Other Options Are Wrong:
Q S R P: This begins with forelimbs and then abruptly shifts to length, teeth and dental battery. It disrupts the natural progression from general to specific features and puts limb details before basic size information.
R Q P S: Placing Q after R before P separates “These teeth” in P from their introduction in R, weakening the pronoun reference. Also, S appears last among the middle sentences even though size is usually mentioned early.
P Q S R and similar orders start with P, where “These teeth” appear without any prior mention of teeth, so the pronoun reference becomes unclear. This violates normal cohesion rules.

Common Pitfalls:
Students may overlook pronoun references such as “These teeth” and place the sentence P too early. They may also ignore how scientific texts often structure descriptions, with length and general form first, followed by specific features. To avoid these errors, always check what each pronoun refers to and look for standard descriptive patterns: overall size, then detail, then comparison.

Final Answer:
The correct sequence is S R P Q, so the correct option is “S R P Q”.