Hello Everyone!

I have a doubt in this question.

While measuring Quantity B (The number of distinct prime factors of 210) should we consider all the distinct primes including their negative counterparts?

If so why? if not why?

The answer in manhattan prep is that you should only take the positive factors.

Ive attached the screenshot of the question. You can see the question also on 5lb GRE by manhattan prep ch Divisibility and Primes Q 3