Answer and Explanation:
The sentence "The advertising must be truthful, or the newspaper will refuse it" is a compound sentence.
A compound sentence is formed by combining two independent clauses (complete thoughts) with a coordinating conjunction or a semicolon. In this case, we have two independent clauses: "The advertising must be truthful" and "the newspaper will refuse it." These clauses are joined by the coordinating conjunction "or."
Therefore, the sentence is compound because it consists of two independent clauses joined by a coordinating conjunction.