The question is not asking you to find possible values of (m,n). You are not required to do this at all. All you need to find out is whether 2m -3n = 0
Rewrite the question prompt as -
=> 2m = 3n
=> m/n = 3/2
Statement 1 - m != 0; This tells us nothing about 'n'. Insufficient.
Statement 2 - 6m = 9n => m/n = 3/2 ; The ratio m/n is same as that in the question prompt. Sufficient.
I probably complicate myself but still wish to clarify if this can be E.
Since the question didn't indicate it is m & n are both INTEGER, so put fraction into considerations as well.
When I put in
m = 2, n = 3 or m = 1/2, n = 1/3, B comes valid...so isn't it a vague question? or I missed any important step? pls advise..thanks