Final answer:
The sentence in question is a simple sentence with a subordinate clause, not complex or compound. It contains a main clause and additional information provided by the subordinate clause.
Step-by-step explanation:
The sentence "He trudged on, though he was tired" is not a compound or complex sentence, but rather a simple sentence with a subordinate clause. This sentence structure, which consists of a main clause and a subordinate clause, is often used to add additional information about the main action without the complexity of a compound or a more intricate complex sentence. In this particular sentence, "He trudged on" serves as the main clause, while "though he was tired" functions as the subordinate clause, providing a reason for the action but not forming a complete sentence on its own.