Which sentence correctly uses a semicolon?

The chosen sentence correctly uses a semicolon to join two independent clauses, which are complete thoughts that can stand alone as separate sentences. In this case, "I have a big test tomorrow" and "I can't go out tonight" are both independent clauses. By using a semicolon, the writer effectively connects related ideas while maintaining clarity and avoiding the use of a coordinating conjunction.

Semicolons are useful for linking related thoughts without the need for conjunctions, and they help in creating a smooth transition between closely related statements. This technique enriches the writing by showing the relationship between the two clauses while also indicating a pause that is stronger than a comma but weaker than a period.

In contrast, the other sentences either misuse the semicolon or fail to meet the grammatical requirements for its use, such as having independent clauses on both sides of the semicolon.