Answer: a. Good hygiene is important for staying healthy; likewise, a balanced diet is essential for good health.
Explanation: From the given options, the sentence that correctly uses a semicolon and a conjunctive adverb to link two or more closely related independent clauses is the corresponding to option a: "Good hygiene is important for staying healthy; likewise, a balanced diet is essential for good health," because when linking two independent clauses with a conjunctive adverb (in this case "Likewise") we need to put a semicolon before the adverb and a comma after.
