**Concept:** **The question tests on basics of Number properties**

**Solution:**

Let x = AB/MN, where N is negative and x is positive.

For x to be positive, both Numerator and Denominator have to be both positive or both have to be negative.

Denominator is Negative: Then (a) M is positive and A positive, B negative or (b) M positive, A negative and B positive

Denominator is Positive: Then (a) M is negative and A positive, B positive or (b) M negative, A negative and B negative

Option B