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In the Official CWNA Study Guide, question 13 of chapter 4 reads:

What are some of the possible negative effects of an impendence [sic] mismatch? (Choose all that apply.)

A. Signal reflection

B. Blockage of the Fresnel zone

C. Erratic signal strength

D. Decreased signal amplitude

E. Amplifier/transmitter failure

I chose ACDE, but the book says the correct answer is CDE. Why is A not one of the answers?

I assume a possible reason is because they question-writer wants to differentiate signal reflection from voltage reflection? Even if that is true, signal reflection should still technically be correct, no?

Although reflections in the radio-to-antenna connection increase, I think what the question is asking is, does the impedance mismatch cause signals from the transmitter- to-receiver experience more reflections.   The answer in that case is obviously no in the radiated case.

A possible "hint" as to the direction of the question might be the inclusion of the Fresnel Zone answer.

This is one of the reasons to take all of the official practice exams you can - to become accustomed to the "style" of the questions.   

Which is why I personally want to see more CWDP (and CWAP) practice questions.

Thanks for the advice. I will look through as many practice exam problems as possible.

I still take issue with the word choice in the question though. Please correct me if I'm wrong, but isn't the term "impedance mismatch" more commonly associated to radio-to-antennas, transmission lines, VSWR, etc? And not the transmitter-to-receiver link?

You are correct.  And I agree that it is a difficultly worded question.    I'm not sure how it should have been worded to test the understanding that they were looking for.

Given the "correct" answers,  I took it to mean "... if the wired impedances are poorly matched, then that would cause a problem with the radiated signals".