The correct answer is "etymology"
Etymology is the science of word origin. Not to be mixed with etiology the science of origin and causation in general.
A similar quote "No One Wants Adviceonly Corroboration<span> " </span>
C.
Why A and D do not work: A thesis is not plot.
Why B does not work: A thesis is not a description of the type of the book.
Answer:
warmly but not too familiarly