Answer:
a. I hung a picture in the new conference room; it brightens the room.
Step-by-step explanation:
In this option, a semicolon is being used to separate two independent clauses without the use of a conjunction. This is grammatically correct. A semicolon can also be used when presenting a serial list, particularly if the items in this list are long or have internal punctuation. Finally, the semicolon can be used when a conjunctive adverb links two independent clauses.