The correct command to generate a 4096-bit RSA key is:
bash
ssh-keygen -t rsa -b 4096
This command:
* -t rsa: Specifies RSA key type
* -b 4096: Specifies key size in bits
During the prompt, the user will be asked if they want to set a passphrase (password), fulfilling the password protection requirement.
* Option A has invalid flags (-RPb).
* Option C uses incorrect and non-existent flags (-k, -l, -p in this context).
* Option D incorrectly uses DSA (which is deprecated and does not support 4096 bits).
Reference: CompTIA Linux+ XK0-005 Official Study Guide, Domain 3.2 - Implement identity and access management:
"Use ssh-keygen -t rsa -b 4096 to generate a secure RSA key. When prompted, set a passphrase for password protection."