Briefing Huawei Knowledge

Which of the following describes the likely reason for this?

An administrator discovered he/she was unable to use TFTP to transfer files to the router.
Which of the following describes the likely reason for this?

A.
The TFTP service had been disabled on the router.

B.
TCP port 69 of the server had been blocked.

C.
UDP port 69 of the server had been blocked.

D.
The username and password had been modified.

Explanation: