Answer:
Because America already existed and was already there with indigenous people occupying it, therefore he was entering and possibly invading it rather than discovering it
Explanation:
Rule 1. A subject will come before a phrase beginning with of. This is a key rule for understanding subjects. The word of is the culprit in many, perhaps most, subject-verb mistakes.
A bouquet of yellow roses lends color and fragrance to the room.
Rule 2. Two singular subjects connected by or, either/or, or neither/nor require a singular verb.
My aunt or my uncle is arriving by train today.
