Suppose you have read two different books on world war ii, and each book has different arguments about how the war started. which of the following would be most useful in evaluating each argument?   a. determine which author used the most persuasive language   b. determine which author used more sources   c. determine which author used the most reliable sources   d. determine which author wrote the longest book

C. Determine which author used the most reliable sources 

It is not A, because: just because they win the crowds doesn't mean there right
An example of that is Adolf Hitler. He won most of the crowds while the Great Depression was happening, and then maintained power with that.

It is not B, because: Some of the sources can giving wrong information or have too much personal opinions.

It is not D, because: Just because it is the LONGEST book, doesn't mean it is correct. The person can just fill the book with non-proven information or even off-topic info

hope this helps