Fill in the blank with the plural form of the nouns given in the bracket.
The horse’s _____________ need cleaning. (HOOF)

The correct answer is: Hooves

Regular nouns become plural by adding -s or -es to the ending of the noun. Irregular nouns do not follow the same rules as regular nouns when becoming plural. 'The horse's hooves need cleaning', here the plural form of hoof is hooves, and it is irregular noun. When the word ends in 'f', in plural form 'ves' is added instead of 'f'.