复数名词后面必须跟复数名词吗?

680. Recent interdisciplinary studies advance the argument that emotions, including those deemed personal or private is a social phenomenon, though one inseparable from bodily response.

A. private is a social phenomenon, though one inseparable

B. private, are social phenomena that are inseparable

C. private are a social phenomenon but are not those separable

D. private—are social phenomena but not separable

E. also as private emotions, are social phenomena not inseparable

选项C中，emotions are a social phenomenon这种说法可以吗？还是说必须复数名词are复数形式的东西？

Eg：Oranges are a tasaty fruit这样说对吗？