The sentence that uses a semicolon correctly is, "Everyone was looking at the ice sculpture as it melted; therefore, no one saw the table tip over." This sentence is an example of a compound sentence. A compound sentence consists of two independent clauses. The independent clauses here are, "Everyone was looking at the ice sculpture as it melted" and "therefore, no one saw the table tip over." We used the semicolon in this sentence to join two complete sentences. And take note that the word "therefore" is not a conjunction because it cannot connect two different sentences just like the words "and" and "but".
