Which of the following connector types would Sandy, a network technician, use to connect a serial cable?

RJ-11 is a 6-position modular plug connector used for analog telephone lines and dial-up modem connections, not for serial RS-232 cables.

BNC (Bayonet Neill-Concelman) is a coaxial cable connector historically used in 10Base2 Ethernet and still used in RF, video, and test equipment applications - not for serial data cables.

LC (Lucent Connector) is a small form-factor fiber optic connector used with single-mode and multimode fiber cable, not with serial copper cables.

The DB-9 (technically DE-9) connector is a 9-pin D-subminiature connector that implements the RS-232 serial communication standard, commonly used for serial console access to routers, switches, and servers. It is the correct connector for a serial cable and remains the industry standard for out-of-band management via serial connections.