A compound-complex sentence contains at least two independent clauses and one or more dependent clauses.
In the provided options:
- A has an independent clause ("the government started an investigation") and another independent clause ("no one expected to find anything"), along with the dependent clause ("After the massacre occurred").
The other sentences are either simple or compound but do not meet the criteria for a compound-complex sentence.
Therefore, the answer is A: "After the massacre occurred, the government started an investigation, but no one expected to find anything."