heheh... I checked these forums, and found that this question has been discussed before. Here is the link - http://www.gmatclub.com/phpbb/viewtopic.php?t=8032&highlight=historian+learn+medical+history+individuals+chemical
As I can see it, both A and B uses qualifiers - "None" in the case of A, and "Some" in the case of B. Therein lies the confusion. I gave B a second thought. I originally rejected B, because on negating B, I got Some people in Beethoven's time did
ingest mercury, which doesn't really make sense. On the other hand, if get the following sentence on negation - Everyone in Beethoven's time ingested mercury, then the argument completely falls apart. As the link I provided notes, this is a very tricky CR, and one can argue both ways.
MORAL OF STORY - Be extremely careful when you deal with qualifiers. Given A and B, one can discard A, because it is more EXTREME of the two.
What concerns me the most is that I will most likely chose the wrong answer choice - A, in a heartbeat, on test day.
Hope the discussion thread I pasted helps you understand this question type better.
hik, are you sure?!!
. I lay my trust on you