This scenario precisely matches Time-Based Blind SQL Injection, a technique detailed in CEH v13 Web Application Hacking. When applications suppress error messages and sanitize outputs, attackers rely on response timing to infer whether injected SQL statements are executed.
In time-based SQL injection, the attacker injects database-specific delay functions (such as WAITFOR DELAY, DBMS_LOCK.SLEEP, or SLEEP()). If the injected condition is true, the database pauses execution, causing a noticeable delay.
The key indicators described-no visible output but increased response time-are classic signs of time- based SQL injection. CEH v13 explains that this method is particularly useful when:
* Errors are hidden
* UNION queries fail
* Output is not reflected
Union-based and out-of-band SQL injections require data exfiltration channels or visible outputs, which are absent here. "Heavy query-based" is not a formal CEH classification.
Thus, Option A is the correct answer.