A) Sufficient, since value of x is given
B)Not sufficient. X does not have a unique value.
IMO: OPTION A

n = 100,000 + m

n and m increase by x percent which can be written as n*(1 + (x/100)) and m*(1 + (x/100)).

Stmt 1: x = 10, so, increases are n(1.1) and m(1.1), so n*(1.1) = (100,000 + m)*(1.1) = 110,000 + m*(1.1), so difference after increased populations can be found. Hence Sufficient.

Stmt 2: m = (10/11)*n
So, n = 100,000 + (10/11)*n which means, we can solve for n and m. However, questions asks about difference in populations after x percent increase, and there is no information about x in this statement. Hence Insufficient.

Hence Option A

C is the right answer