A Red Team Initiated a DoS Attack on the Management

A red team initiated a DoS attack on the management interface of a switch using a known vulnerability. The monitoring solution then raised an alert, prompting a network engineer to log in to the switch to diagnose the issue. When the engineer logged in, the red team was able to capture the credentials and subsequently log in to the switch. Which of the following actions should the network team take to prevent this type of breach from reoccurring?

A) Encrypt all communications with TLS 1.3.
B) Transition from SNMPv2c to SNMPv3 with AES-256.
C) Enable Secure Shell and disable Telnet.
D) Use a password manager with complex passwords.