Pronoun case for who and whom

23a. Jon Bon Jovi, who is a well-known singer and actor, also owns an arena football team.

23b. Jon Bon Jovi, whom is a well-known singer and actor, also owns an arena football team.

My answer is 23a

Yes

Yep. :-)

that is wrong

The correct pronoun case to use in this sentence is 23a, which says "Jon Bon Jovi, who is a well-known singer and actor, also owns an arena football team." Here's an explanation for why 23b is incorrect:

To determine whether to use "who" or "whom," you need to understand the subject and object roles in the sentence.

In this case, Jon Bon Jovi is the subject of the sentence (the one performing the action of owning an arena football team). Since "who" is used to refer to the subject of a sentence, it is the correct pronoun to use here.

On the other hand, "whom" is used to refer to the object of a sentence or a preposition. In 23b, the sentence says "Jon Bon Jovi, whom is a well-known singer and actor." Here, "whom" is incorrectly used as the subject pronoun, when it should be "who."

So, in conclusion, the correct pronoun case to use in this sentence is "who," as seen in 23a.