Options: (i) apart (ii) swamp vegetation (iii) layers of fat (iv) social groups (v) alone (vi) salt and water. (vii) separately (viii) competition

You are presented with the quiz "what do lions live in?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "lions live in social groups called prides" and "lions hunt in prides, the killing is usually done by the swifter young lions". So, what's the best answer to the question?
Answer:
(iv)