In the argument, the critics mistake correlation for causation. While it is true that most employees were reassigned to the mission to Mars, it is not established that the mission to Europa was scrapped to move the employees to a different project; it’s possible that some other motivation caused the demise of the Europa project. NASA claims that its critics are misinformed.

(A) Irrelevant. The conclusion is based on the critics’ assumption of causation, and this choice fails to address the issue of the motivations underlying NASA’s decision-making process. That the percentage of spending is going to decrease could indicate many possible scenarios, including that NASA is unhappy with the progress of the project and plans to cut future spending or that the organization expects the development of the shuttle to be completed by 2018.

(B) Weakens. If public interest determines its budget, NASA has strong motivation to keep public interest high. Additionally, “budget” is not mentioned in the original argument.

(C) Irrelevant. This statement differentiates between the opinions of some scientists and the opinions of others, but sheds no light on the motivations behind NASA’s decisions.

(D) CORRECT. This answer choice provides an alternative explanation for the decision to abandon the attempt to send an unmanned vessel to Europa; the Tokyo telescope will provide the information that NASA would have obtained from the mission, making the mission unnecessary.

(E) Irrelevant. The conclusion concerns NASA’s motivations; this statement is about the motivations of American citizens. There is no direct relationship between what Americans see as the future of space exploration and the motivations behind NASA’s decision making.