which of the following describes a gerund and how it functions in a sentence?
a. A gerund is a noun that functions as the direct object receiving the action in a sentence.
b. A gerund is a verb ending in -ing that functions as a verb in a sentence.
c. A gerund is a noun that functions as the subject of the sentence.
d. A gerund is a verb ending in -ing that functions as a noun in a sentence