D
Pure science -- research with no immediate commercial or technological application -- is a public good. Such research requires a great amount of financial support and does not yield profits in the short term. Since private corporations will not undertake to support activities that do not yield short-term profits, a society that wants to reap the benefits of pure science ought to use public funds to support such research. The claim about private corporations serves which one of the following functions in the argument?
A: It distracts attention from the point at issue by introducing a different but related goal.
B: It expresses the conclusion of the argument.
C: It explains what is meant by the expression "pure research" in the context of the argument.
D: It supports the conclusion by ruling out an alternative way of achieving the benefits mentioned.