Answer:
All of the fruit looks ripe.
Step-by-step explanation:
The singular subject is referred to the subject which is singular in number. The verb used with them is singular. If the noun used after the preposition 'of' is singular, the verb used is also singular. In the fourth sentence, the noun used after 'of' is 'fruit'. 'Fruit' is singular in number and it also uses the singular verb 'looks'. All the other three sentences have plural subjects.