Final answer:
The sentence is a compound sentence as it contains two independent clauses connected by the coordinating conjunction 'but'.
Step-by-step explanation:
The sentence in question is: The clock's minute hand is moving, but the second hand has stopped. This is an example of a compound sentence because it consists of two independent clauses joined by the coordinating conjunction 'but'. An independent clause has a subject and a verb and can stand alone as a complete thought. Here we have two of them: The clock's minute hand is moving and the second hand has stopped, showing two separate but related ideas.