Which does the sentence contain?

a conjunction

a gerund

an infinitive

a participle

This question is incomplete, since it is missing the sentence we are supposed to analyze. I've found the complete question online. It is as follows:

"To the best of our knowledge, he decided that his major would be acting." Which does the sentence contain?

a) a conjunction

b) a gerund

c) an infinitive

d) a participle

Answer:

The sentence contains letter b) a gerund.

Explanation:

Gerunds are formed by adding - ing to verbs, but they function like nouns in a sentence.

In "To the best of our knowledge, he decided that his major would be acting," we have the verb "be" functioning as a linking verb, connecting the subject "major" to a word or words that provide information about that it. That word providing information on the subject is the gerund "acting", which therefore functions as a subject complement in this sentence.