Which statement best evaluates the author's logic?

a. the author fails to use citations throughout, leaving the reader to wonder where his information comes from.
b. the author's work contains several misspellings and grammatical errors that are very distracting to the reader.
c. the author comes to various outlandish conclusions that lead the reader to question his credibility.
d. the author jumps from one topic to the next, taking the audience on a roller coaster ride of information

C).  The author comes to various outlandish conclusions that lead the reader to question his credibility.

Explanation:

Authors employ several techniques to persuade or convince the audience to accept and believe in the claims or ideas proposed by the author. Logic or reason is one of these techniques which is quite significant to establish the credibility of the claim and conclusion.

As per the question, the statement that best assesses the author's logic is displayed through option B as it displays that the author has reached 'quirky or outlandish conclusions' which goes offbeat due to lacking reason or logic and thus, 'compels the readers to question his credibility'. Therefore, the claims presented in an essay or text must have a logic and coherence among them to establish the argument before the readers. Thus, option C is the correct answer. The other options has no affiliation to logic.