The answer would be B, complex.
Compound is two complete sentences that is combined by a coordinating conjunction such as but, for, and, etc. For example, "I waited for Lisa at the bus station, BUT the bus didn't arrive until noon and so I left.
Simple means that a sentence uses just a subject and a verb. For example, "The bus was late" subject=bus; verb=was
Complex is a sentence that has a independent clause and one or more dependent clause. The dependent clause starts with a subordinating conjunctions which are as, after, because, etc.
In this particular sentence, it starts with As and, it has a independent clause which is "He returned to his village"