Rearrange the four labelled sentences P, Q, R and S to form a coherent paragraph about the changing pattern of human disease. Then select the most logical order of the sentences from the options given below. P: Modern medicine has scored significant victories against both infection and trauma, and the major causes of ill health and death are now the chronic degenerative diseases, such as coronary artery disease, arthritis, osteoporosis, Alzheimer disease, macular degeneration, cataract and cancer. Q: It follows that the majority of apparently healthy people are in a pre-ill state. R: Throughout human history, the leading causes of death have been infection and trauma. S: These chronic degenerative diseases have a long latency period before symptoms appear and a diagnosis is made.

Introduction / Context:
This question is a classic sentence arrangement or para jumble item. Four labelled sentences P, Q, R and S talk about the changing pattern of human disease from infections and trauma to modern chronic degenerative diseases. The task is to arrange these sentences so that they form one smooth, logically connected paragraph.

Given Data / Assumptions:

• R says that throughout human history the leading causes of death have been infection and trauma.
• P states that modern medicine has scored significant victories against infection and trauma and that chronic degenerative diseases are now the main causes of ill health and death.
• S explains that these chronic degenerative diseases have a long latency period before symptoms appear and a diagnosis is made.
• Q concludes that the majority of apparently healthy people are actually in a pre ill state.
• We assume that a coherent paragraph should move from historical background to present situation, then to explanation, and finally to a logical inference.

Concept / Approach:
The correct approach in para jumbles is to look for (a) an opening sentence that introduces the topic, (b) clear logical links such as pronouns and demonstratives, and (c) a concluding inference. Sentence R clearly introduces the topic with a time phrase throughout human history. Sentence P continues naturally by contrasting the past with the present after the advances of modern medicine. Sentence S refers back to the chronic degenerative diseases mentioned in P through the pronoun these. Finally, sentence Q draws a conclusion from S by using it follows that. Putting these observations together leads to the order R P S Q.

Step-by-Step Solution:
Step 1: Identify the best opening sentence. R is the only sentence that begins with a broad time frame throughout human history and sets up the background, so R should come first.Step 2: Look for a sentence that contrasts the historical situation with the present. P begins with modern medicine and describes the new pattern of disease, so it logically follows R, giving RP.Step 3: Observe the demonstrative pronoun these in S, which must refer back to the chronic degenerative diseases listed in P. Therefore S must follow P, giving RPS.Step 4: Sentence Q uses the connector it follows that to draw an inference from the information about latency periods and hidden disease risk in S. So Q comes last, giving the full order RPSQ.Step 5: Check the flow: R (past pattern) → P (present pattern) → S (key property of present diseases) → Q (conclusion about apparently healthy people). This is smooth and logically tight.

Verification / Alternative check:
Test competing options. If P is placed first, there is no prior context for the contrast between modern medicine and earlier times. If Q appears earlier, the phrase it follows that would lack a clear previous statement to follow from. Any order that puts S before P leaves the pronoun these without a proper noun phrase to refer to. Only RPSQ satisfies all pronoun references and gives a natural progression from history to conclusion, which confirms it as the best sequence.

Why Other Options Are Wrong:
PRQS starts with P and jumps backwards to R, which breaks the time sequence from past to present. PSQR makes P the opener and then gives S, but has no place to introduce infection and trauma as traditional killers. QRSP begins with a conclusion, which is unnatural and leaves the reader wondering what it follows from. None of these alternatives maintains both the historical contrast and the logical chain of reference that we see in RPSQ.

Common Pitfalls:
Many learners focus only on content words like disease or health and ignore linking phrases such as throughout human history, these and it follows that. In para jumbles, these linking words are often the strongest clues. A useful strategy is to first locate the global introduction and the clear conclusion, then arrange the remaining sentences using pronouns and logical connectors as guides.

Final Answer:
The most logical and coherent order of the sentences is RPSQ, so option A is correct.