Answer:
I have a big test tomorrow; I can't go out tonight.
Explanation:
When you have a conjunctive adverb linking two independent clauses, you should use a semicolon.
Answer:
Mutations
Explanation:
A gene mutation is a permanent change in the DNA sequence of a gene. Mutations can occur in a single base pair or in a large segment of a chromosome and even span multiple genes. Mutations can result from endogenous (occurring during DNA replication) or exogenous (environmental) factors.
I believe the answer is B