The verb "work" is plural, indicating multiple teachers. The sentence requires a plural subject.

Here are the correct answers:

1. The verb "work" is plural, indicating multiple teachers. The sentence requires a plural subject.

   • a) teachers

2. "Name" belongs to "sister". The sentence implies one sister.

   • b) sister's

3. The verb "are visiting" is plural, indicating multiple friends. The sentence requires a plural subject.

   • a) friends

4. "House" belongs to "uncle". The second part of the sentence "I only have one" confirms it's a singular uncle.

   • c) uncle's / uncle

5. "Hats" belong to "children". "Children" is an irregular plural noun, so its possessive form is "children's".

   • c) children's

6. "Clothing" belongs to "men". "Men" is an irregular plural noun, so its possessive form is "men's".

   • d) men's