D. A semicolon can be used where you might use a period.
Explanation:
A semicolon can be used where you might used a period if the two sentences are related to each other. Also semicolons are used before words such namely, however, therefore. Semicolons are used to join two independent clauses that are similar/closely related to each other especially those joined by a words which are connectors like and, but, or, nor, e.t.c. If a sentence contain many commas, it is suitable to add a semicolon.
