A Biped is related to a Quadruped based on the number of legs. In the same way, an Ostrich is related to which of the following animals?

Introduction / Context:
This analogy is about classification by number of legs. A Biped is a creature that walks on two legs, while a Quadruped walks on four. You must extend that classification idea to Ostrich and choose the animal that best completes the pattern.

Given Data / Assumptions:
1) Biped refers to any animal or human that walks on two legs, such as humans or birds like ostriches.

Concept / Approach:
The first pair, Biped and Quadruped, links a two legged being with a four legged being. Ostrich is clearly a two legged bird. To preserve the analogy, we must pair Ostrich with an animal that represents a typical four legged creature. Among the choices, Cat is a standard four legged mammal, while the others have different numbers of legs or are also two legged birds.

Step-by-Step Solution:
Step 1: Recognise that the relationship Biped : Quadruped is based on number of legs, that is two versus four. Step 2: Recall that an Ostrich is a large bird that walks and runs on two legs. Step 3: Examine the options. Cat is a typical four legged mammal. Kangaroo mainly moves by hopping and is not described by a special term like quadruped in this context. Penguin and Duck are birds that also use two legs. Step 4: The only clearly four legged animal that can pair with a two legged Ostrich is Cat. Step 5: Therefore the correct analogy is Ostrich : Cat.

Verification / Alternative check:
You can verify by writing each pair with numbers. Biped has 2 legs, Quadruped has 4 legs. Ostrich has 2 legs, so its pair should have 4 legs. Among the options, Cat has 4 legs in normal movement. The other options either share the same number of legs as Ostrich or do not represent the category contrast as clearly, so they fail to maintain the structure of the analogy.

Why Other Options Are Wrong:
Kangaroo is a two legged jumper but is not a standard label for four legged creatures. Penguin and Duck are birds with two legs, so they match Ostrich too closely instead of giving a contrasting class like Quadruped. The analogy is about contrasting two legged and four legged animals, so selecting another two legged bird would break the pattern.

Common Pitfalls:
A common error is to pick another bird such as Duck or Penguin, because students focus on category of animal rather than the number of legs. The key, however, is to notice the leg based classification in the first pair. Once you see that, it becomes clear that a four legged mammal like Cat is the proper choice.

Final Answer:
Hence, the correct completion of the analogy is Ostrich : Cat. Biped is to Quadruped as Ostrich is to Cat.