Question

read the sentence and determine which revision, if any, is necessary.
valentinas mother an art history professor often gives lectures at the local museum.
the phrase \an art history professor\ should be set off with commas.
the phrase \at the local museum\ should be set off with a comma.
the phrase \valentinas mother\ should be set off with a comma.
the sentence is correct as written.

Explanation:

The phrase "an art history professor" is a non-restrictive appositive that provides extra, non-essential information about Valentina's mother. Non-restrictive appositives need to be set off from the main clause with commas. The other options are incorrect: "at the local museum" is a prepositional phrase that doesn't need commas, "Valentina's mother" is the main subject and can't be set off, and the original sentence is grammatically incomplete without commas around the appositive.

Answer:

A. The phrase "an art history professor" should be set off with commas.