Fill in the gaps with the correct form of a possessive adjective or a possessive pronoun. My cousins have got a lot of toys. They are _______ toys.

Their

Explanation:

The sentence 'My cousins have got a lot of toys. They are their toys' uses the possessive adjective 'their' to show that the toys belong to 'my cousins'. 'Their' is the correct form to indicate possession by a plural noun.