Question

which smtp command would be easiest to disable to prevent attackers from misusing it for enumeration? a rcpt to b mail from c vrfy d data

Explanation:

The VRFY (Verify) command in SMTP is often misused by attackers for enumerating valid email addresses on a server. Disabling it is a common - sense security measure as it is not a critical command for normal email - sending operations and is easily disabled compared to other commands like RCPT TO, MAIL FROM, and DATA which are more integral to the email - sending process.

Answer:

C. VRFY