Answer:
A.
Step-by-step explanation:
1. Complex sentence: Has one independent clause and 1 (or more) dependent clauses
2. Clause: Contains a subject and verb
3. Independent Clause: Taking the clause out of the sentence would make sense as a sentence on its own.
4. Dependent Clause: Even though it has a subject and verb, it doesn't make sense as a sentence.
Not B: This is a compound sentence. It has 2 independent clauses. I know this because If you take "I really wanted to go to my friend's house" and "I stayed at home," they can be their own sentence.
Not C: This is similar to a complex sentence, so it can be trickier. It's not because "as a result of the storm" doesn't have a subject or verb so it's nto a clause.
Not D: Before and after the semicolon can be their own sentence. Because they're both independent, it's compound and not complex.
It's A: "After the storm subsided" doesn't make sense by itself, but it has a subject (storm) and verb (subsided). That makes it dependent. The other is independent because it makes sense as a sentence. Independent clause+dependent clause= complex.