Срочно помогите пожалуйста

Choose the right variant:
1. a knife
А) knifes
B) knifs
C) knives

2. a watch
А) watches
B) watchs
С) watch
3. а child
A) childrens
B) childes
C) children

4. a foot
A) foots
B) footes
C) feet

5. a tooth
A) teeth
B) tooths
C) teeths

6. a photo
A) photos
B) a photos
C) photo

7. a sheep
A) sheeps
B) sheep
C) sheepes

8. а businessman
А) businessmens
B) businessmans
C) businessmen

9. a mother-in-law
A) mothers-in-law
B) mother- in-laws
C) mothers-in-laws

10. a datum
A) data
B) datas
C) datums