"is" versus "are"

Which one is correct grammar:

"What are the agent, object, and environment in this study?"

"What is the agent, object, and environment in this study?"

Rule 4. As a general rule, use a plural verb with two or more subjects when they are connected by and.

Example: A car and a bike are my means of transportation.

But note these exceptions:

Exceptions:
Breaking and entering is against the law.
The bed and breakfast was charming.

In those sentences, breaking and entering and bed and breakfast are compound nouns.

1. When the subject of a sentence is composed of two or more nouns or pronouns connected by and, use a plural verb.

She and her friends are at the fair.
2. When two or more singular nouns or pronouns are connected by or or nor, use a singular verb.

The book or the pen is in the drawer.
3. When a compound subject contains both a singular and a plural noun or pronoun joined by or or nor, the verb should agree with the part of the subject that is nearer the verb.

The boy or his friends run every day.
His friends or the boy runs every day.

I disagree.