Question

Which of the following is not an option for joining two independent clauses to make a compound sentence?

comma + coordinating conjunction
comma
semicolon + conjunctive adverb + comma. semicolon

Answer 1

The option not used for joining two independent clauses to make a compound sentence is comma. Comma is used for joinign dependent clauses or clauses that cannot stand alone or do not make sense when detached from the parent sentence. In this case, the answer would be B

Answer 2

The correct answer is comma.
You cannot join two independent clauses in order to make a compound sentence just by using a comma. If you only use a comma (without any conjunctions), then this is going to be a run-on sentence.
For example:
I saw a boy at school, I think he is the most beautiful boy in the world.
Because you didn't use a conjunction (and) or a semicolon, this sentence is compound, but it is incorrect.