THE CORRECT ANSWER IS B. THE CONCLUSION OF THE ARGUMENT IS THAT MI...
13. The correct answer is B.
The conclusion of the argument is that Michelangelo must have
completed the painting between 1507 and 1509. The basis for that
claim is that the painting depicts a coin that did not exist before
1507 and that it contains a pigment that Michelangelo ceased using
in 1509. We are asked to find an assumption that completes the
logic of this argument.
Choice A is incorrect. We do not need to assume that no stocks of
the pigment existed after 1509. The argument is concerned only
with the year in which Michelangelo stopped using the pigment.
Choice B is correct. In order to conclude that the painting must have
been completed before 1509 on the basis of the pigment, we must
assume that he did not begin the painting before 1509 using the old
pigment and complete the painting after 1509 with the new
pigment.
Choice C is incorrect. The fact that the general public knew of the
coin in 1507 is irrelevant to the conclusion.
Choice D is incorrect. The fact that the panel cannot be tested for
age does not relate to either the coin or the pigment, the two bases
for the conclusion.
Choice E is incorrect. Whether Michelangelo's painting style changed
during this period does not relate to either the coin or the pigment.