As a practical matter, the copper available for industrial use should not be thought of as limited by the quantity of copper deposits, known or unknown. The transmutation of one chemical element into another is a modern reality, through the methods of nuclear physics. Therefore, the quantity of a natural resource such as copper cannot be calculated even in principle, because copper can be made from other metals.
Which of the following, if true, is the strongest argument against the argument above?
A) Although it is possible that additional deposits of copper will be found, geological considerations strongly indiate that they will not amoun to more than fifty-year supply.
B) The production of copper from other metals in industrial quantities would be prohibitively expensive in energy and materials.
C) Synthetic materials have been discovered that can serve as practical substitutes for copper in most of its uses.
D) It will be impractical, in the foreseeable future, to mine any deposits of metal that may exist on the moon or on other planets.
E) Methods for estimating the amount of copper avialable in currently known deposits have become very sophisticated and have proved some accurate

I chose A. However A is not the answer. In order to weaken, we should state that the copper won't be forever, something like this. I think that's what A says. What do you think? OA to follow.