GMAT Probability and Number Theory Problem Solving Question

Question 4 of the Q-51 hard math series by 4GMAT. Concept tested primarily number of factors of a positive integer and probability. GMAT Practice. GMAT problem solving question. If two distinct integers a and b are picked from the first 100 positive integers and multiplied, what is the probability that the resulting number has EXACTLY 3 factors? A. 4/(25*99) B. 2/(25*99) C. 8/(25*99) D. 16/(25*99) E. 32/(25*99)