Which rule best explains why the verb in the following sentence is correct?

publishing and presenting is the final stage of the writing process.

a singular verb is used because the two parts of the compound subject are thought of as a single item.
a singular verb is used because a compound subject connected by and needs to agree with the subject that is closer.
a singular verb is used because both parts of the compound subject connected by or are singular.
a singular verb is used because a singular indefinite pronoun comes before the compound subject.