The correct answer is C because DEP, or Data Execution Prevention, is a memory-protection control that prevents code from executing from memory regions intended only for data storage, such as stack or heap/data memory. In CEH system exploitation and buffer overflow concepts, attackers may try to inject malicious shellcode into a buffer and then redirect program execution to that injected code. The CEH-aligned material explains that buffer overflow attacks can overwrite adjacent memory and allow different executable code to run; it also notes that ASLR and DEP are common defenses against these memory-management attacks. EC-Council material also states that buffer overflow exploitation depends on a machine being able to execute code in the data/stack segment, and lists disabling stack execution as a defense. Therefore, DEP does not block encryption, logging, or scanning. It specifically blocks execution from data memory areas.