Question ID:PT56 S2 Q8 Passage:This boulder is volcanic in origin and yet the rest of the rock in this area is sedimentary. Since this area was covered by southward-moving glaciers during the last ice age, this boulder was probably deposited here, hundreds of miles from its geological birthplace, by a glacier. Stem:Which one of the following, if true, most seriously undermines the conclusion drawn in the argument above? Correct Answer Choice:DChoice A:Most boulders that have been moved by glaciers have not been moved more than 100 miles. Choice B:The closest geological source of volcanic rock is 50 miles south of this boulder. Choice C:The closest geological source of volcanic rock is 50 miles north of this boulder. Choice D:There are no geological sources of volcanic rock north of this boulder. Choice E:No other boulders of volcanic origin exist within 50 miles of this boulder.