Understanding Animals That Live in Flocks

The question asks us to identify the single word that describes animals which live in flocks or groups.

Let's look at the meanings of the given options:

• pugnacious: This word is used to describe someone or something that is eager or quick to argue, quarrel, or fight. It relates to behaviour, specifically aggression, not how animals group together.
• gregarious: This word is used to describe someone who is fond of company; social. When used for animals, it means living in flocks or loosely organized communities. This definition directly matches the idea of living in flocks.
• amphibious: This word describes an animal that is a cold-blooded vertebrate typically living on land but breeding in water. It can also refer to things able to live both on land and in water. This relates to the habitat of an animal, not its social grouping behaviour.
• migratory: This word is used to describe an animal that migrates at regular intervals, often over long distances. This refers to the movement pattern of an animal, not its social tendency to live in groups or flocks permanently.

Based on the definitions, the word that means living in flocks is gregarious.