Answer:
The sentence that shows correct comma usage is A.
Explanation:
Sentence A is a clear example of the use of a comma before the coordinatinating conjunction and. When two independent clauses are joined by a coordinating conjunction, a comma is required before the conjunction. Otherwise, the sentence becomes a run-on sentence.
An independent clause is clause that represents a complete thought, and can therefore stand alone as a sentence (1 & 2).
1) He graduated from college,
2) And he got his diploma
