Answer: to determine what the facts and details explain about the topic.
Explanation:
A. to learn more about the author of the source
B. to determine what the facts and details explain about the topic
C. to understand how writing works
D. to decide whether the resource is positive or negative
We can learn more about the author of the source.
And we can also determine what the facts and details explain about the topic.
But <u><em>B</em></u> tells more about facts and topics.
So your answer would be "B) to determine what the facts and details explain about the topic."