The shaft in the gear box often becomes less responsive after a few weeks of intense use. A researcher, whose son is a biker, hypothesized that dirt and oil rather than changes in the material properties of the shaft were responsible.

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

A) Determining if a metal alloy is used to make the shaft used by bike racers.

B) Determining whether mountain bikers make their gear-shafts become less responsive faster than do normal bikers

C) Determining whether identical lengths of shafts, of the same dimensions, become less responsive at different rates when used in various brands of bikes

D) Determining whether a dead shaft and a new shaft are able to produce the same RPM

E) Determining whether smearing various substances on new guitar strings causes them to become less responsive.

Source : Crack Verbal Critical Reasoning Guide Illustrative Example

OA: E

Question : I do not understand why E has been choosen as the answer.  The answer choice E seems totally irrelevant to me to be considered as an answer.