Which of these is the properly punctuated sentence?

a)Ted went to work and Bob went home.
b)Ted went to work; and Bob went home.
c)Ted went to work. And Bob went home
d)Ted went to work, and Bob went home.

Would the correct answer be D?

D is correct, yes.

Yes, the correct answer is D. "Ted went to work, and Bob went home." This sentence is properly punctuated with a comma before the coordinating conjunction "and." The comma separates the two independent clauses ("Ted went to work" and "Bob went home") and helps to clarify their relationship.