If the Subject of a Categorical Proposition Begins with the Article

If the subject of a categorical proposition begins with the article "a" (as in "a house") , must the proposition be singular?

A) Yes, because the article "a" guarantees that the proposition is about a single individual.
B) Yes, because grammatically, the article "a" can only be followed by a singular noun.
C) No, because the noun that follows could be intended to represent a class of things.
D) No, because grammatically, the noun that follows could be plural.
E) No, because the article "a" always signals that the proposition is particular.