OG51，OG解释中的一句话没看明白

OG51.

Guitar strings often go “dead”—become less responsive and bright in tone—after a few weeks of intense use. A researcher whose son is a classical guitarist hypothesized that dirt and oil, rather than changes in the material properties of the string, were responsible.

Which of the following investigations is most likely to yield significant information that would help to evaluate the researcher’s hypothesis?

(A) Determining if a metal alloy is used to make the strings used by classical guitarists

(B) Determining whether classical guitarists make their strings go dead faster than do folk guitarists

(C) Determining whether identical lengths of string, of the same gauge, go dead at different rates when strung on various brands of guitars.

(D) Determining whether a dead string and a new string produce different qualities of sound

(E) Determining whether smearing various substances on new guitar strings causes them to go dead

这道题我知道应该选E，按照自己的理解排除起来倒也毫不费力。

但是，OG解释中下面这句话我没明白，请路过的好心人帮忙解释一下吧，谢谢！

Information about the strings' material (choice A) will need considerable supplementation before its bearing on the hypothesis is clear.

谢谢rosmarine！