A penetration tester has gained access to the Chief Executive Officer's (CEO's) internal, corporate email. The next objective is to gain access to the network. Which of the following methods will…

Obtaining an S/MIME private key is used for email signing and encryption, not for direct network-level access to other systems.

Sending an email to request a new account is a social engineering technique that may or may not succeed and does not represent a direct technical method for gaining network access from a compromised server.

Moving laterally from the mail server to the domain controller presupposes the attacker already has sufficient control over the mail server, which is enabled by gaining root access as described in option D.

Gaining root access on the mail server provides the attacker with full control over that system. From a compromised server with root privileges, the attacker can then pivot, move laterally within the network, extract stored credentials, or exploit trusts to access other critical network resources, including domain controllers, thereby achieving broader network access.