How is D the answer?

Hi Tyler, The fact that most people do something is not convincing evidence that the action causes anything else. Take the real world for example. Most people in the industrialized world do indeed use telephones yet don’t have rashes. Let me give you another analogy. 1 Some runners have injuries 2 Most runners wear running shoes The fact that most runners wear running shoes is hardly evidence that the running shoes cause a problem that some of those runners happen to share. The facts in the stimulus + answer choice D are similar to this fact pattern. 1 A problem exists (analogous to the injuries) 2 Most people in the population use the telephone (analogous to the runners wearing running shoes) We are still left wondering whether those two things have any relationship or not.

"Telephones are used by most people in the industrialized world." To me, that supports his diagnosis (this being a bizarro strengthen). If telephones are used by most people in the industrialized world, more than likely his patients got the rash from being on the telephone because most people use telephones, thus supporting his argument.