Answer: The different parts of this complex sentence are:
The prepositional phrase ---> 2. down the road
The independent clause ---> 1. The man sped down the road
The dependent clause ----> 4. until a police officer stopped him
The subordinate conjunction ---> 3. until
Explanation: The sentence provided is a complex sentence because it is made up of an independent clause and a dependent clause. While the independent clause ("The man sped down the road") can stand alone as a sentence, the dependent clause ("until a police officer stopped him") cannot stand by itself. The independent clause contains a prepositional phrase ("down the road") and the dependent clause has been introduced by the subordinating conjunction "until".