GMAT Critical Reasoning (CR) | Most of the world's supply of uranium currently comes from

i can't understand why A is the answer.. i would choose this option only in a "weaken question", but this is an "evaluation question"; my kaplan book says: "The correct answer won't strengthen or weaken the author's reasoning or supply a missing assumption. Instead, the right answer will specify the kind of evidence that you would help you to judge the validity of the author's argument"
this is the reason why i'd chose C
can