Which of the following is not a valid c variable name mcq

Which of the following is not a valid c variable name mcq mcq and its answer is provided on this page.

Which of the following is not a valid c variable name mcq?

Que.	Which of the following is not a valid c variable name mcq
a	var123
b	var_123
c	123var
d	X_123_var
Answer: c
Explanation : A variable name cannot start with a number.