The correct answer is C because the Apache access log is the single evidentiary source that can tie together the request details and the server’s response outcome in one timestamped record. The question requires two things from one place: recovering the attacker-supplied payload and confirming how the server responded. A query string may contain the encoded XML payload, but by itself it does not provide the full evidentiary context such as status code, request timing, source host, and request line. A 200 status code is only one field, not a source. A GET request is a request method, not the artifact repository. Apache access logs routinely record the request line, which can include the query string, along with the response status code and related metadata. That makes them ideal for reconstructing both what the attacker sent and how the server processed it, while keeping timestamps aligned within the same record. In CHFI v11, web application forensics depends heavily on interpreting web server logs to investigate malicious requests, making the Apache access log the strongest answer here.