We can solve this question by options so
By observing options we can say that:-
$\large NOTE$: It is just a pseudocode don't relate it with programming
$\text{/*Number of a's strictly greater than b's*/} $
$if (m>n)\{$
$\text{/*0 b's possible -(C)*/ }$
$if(n==0) C$
$\text{/*0 b's not possible -(D)*/}$
$else\space D$
$\}$
$\text{/*Number of a's greater than b's*/} $
$if(m>=n)\{$
$\text{/*0 b's possible B*/}$
$if(n==0) B$
$\text{/*0 b's not possible A*/}$
$else\space A$
$\}$
$S\longrightarrow XY\longrightarrow X\longrightarrow a$
so we can't prove $\#a = \#b$ it means $(m=n)$
so option A and B eliminated and n is also 0 it means 0 b's also possible so option D eliminated
Hence $\large Option C$ is right answer