Which type of sentence is this: “He made a mistake after he apologized”?

This question asks to identify the type of sentence: "He made a mistake after he apologized." Sentence types are determined by the number and kind of clauses they contain.

• The correct answer is C) Complex sentence. A complex sentence consists of one independent clause and at least one dependent clause. In this sentence, "He made a mistake" is an independent clause (it can stand alone as a complete thought). "after he apologized" is a dependent clause, introduced by the subordinating conjunction "after," and cannot stand alone.
• A) Simple sentence contains only one independent clause.
• B) Compound sentence contains two or more independent clauses joined by a coordinating conjunction.
• D) Complex-compound sentence contains two or more independent clauses and at least one dependent clause.

The presence of one independent and one dependent clause makes it a complex sentence.