Question

An author appeals to logic by _____.

Answer 1

The second statement is the most accurate.
Hope this helps!

Answer 2

The right answer is "providing evidence to back claims "

Thus, the complete sentence is:  "An author appeals to logic by providing evidence to back claims "

To make an appeal to logic, the author has to convince the reader that the position on a subject being exposed is reasonable. For this, it is necessary to justify, to gather facts or examples that have credibility, that is, to present a series of evidences that support the arguments elaborated.