A cat and a rooster B

1. The blank follows 'interrupting' and describes the subject of the interruption. 2. The sentence refers to the rooster's noises. 3. 'people's' is the possessive form, indicating the noises belong to the people, which doesn't fit. 'peoples' is plural of people, also not fitting. 'people' is the plural noun. The sentence is about the rooster interrupting sleep. The rooster's noises are interrupting the sleep of 'people'. 4. 'people' is the correct plural noun.

people