Explanation

This question pertains to three overlapping sets. It helps tremendously to be acquainted with the three-part Venn diagram and set (see the GMAT Free Math Review if you aren't), but the takeaway is that, as we are adding everything up, areas of overlap can get counted twice. If we add up the percentages of people who pass each of the parts and the people who passed none, we get



Which is more than the number of people because some are double counted. We are told one of the double-counting areas: 35% of people passed exactly two areas. If we subtract that from 165% we are down to 130%. The difference is the number of people who have passed all three portions, and this portion is triple-counted, so we need to subtract it twice to count everyone once. That means 30% is twice the percentage who passed all three, which must therefore be 15%. Consequently, the percentage who passed exactly one will be the total minus those who passed neither, exactly two, and exactly three:



That number is 30% of 600, or 180. The correct answer is (B).