Without doing the math, you can tell the answer is A.
50% of 120 pencils is 60 pencils. From there you just use process of elimination. It can't be B because there are over 50% black pencils. There aren't enough pencils in total for the answer to be C and not all penciled are black, so it can't possibly be D. That leaves us with A which is quite close to 50%.
Another method would be multiplying 120 by 60% (round 59%), which equals 72 pencils (A)