different factors

I think the answer is A.

1) Sufficient because factors are:

1 and (a^4)(b^3)
a and (a^3)(b^3)
a^2 and (a^2)(b^3)
a^3 and (a)(b^3)
a^4 and b^3
so on so forth... clearly you can get a distinct countable value for the number of factors.

2) Insufficient because it only states 5 and 7 are prime factors... so:

if n = 35 then the answer to the question is 4 (1, 5, 7, 35)
if n = 165 then the answer to the question is 6 (1, 5, 7, 25, 35, 165)

so therefore insufficient.

yup agree. A