which Cisco IOS debug commands can be issued?

Which prompt indicates the configuration mode at which Cisco IOS debug commands can be issued?

A.
router>

B.
router#

C.
router(config)#

D.
router(config-if)#

Explanation:
You would use privileged EXEC mode, as indicated by the router# prompt, to issue Cisco IOS show and debug commands. All debug commands are entered in
privileged EXEC mode. A brief description of all the debugging commands can be displayed by entering the following command in privileged EXEC mode at the
command line:
debug?
Debugging output consumes high CPU processing power and can leave the system unusable. The debug commands should be reserved to troubleshoot specific
problems, preferably with the help of Cisco technical support staff.
The prompt router> indicates user exec mode, which provides limited access to the router.
The prompt router(config)# indicates global configuration mode, which allows configuration settings affecting the entire router. Passing through this mode is also
required to access configuration mode for specific interfaces as well.
The prompt router(config-if)# indicates interface configuration mode, which allows configuration of the interface specified when entering this mode.
Objective:
Infrastructure Management
Sub-Objective:
Configure and verify device management

Cisco > Support > Cisco IOS Software > Using the Command-Line Interface in Cisco IOS Software