I honestly don't know how many arrests have been made in the chapter 8 of Chasing Lincolns Killer however I might explain to you the summary of the chapter:
<span>Many people, for instance, might think Booth acted alone, and in a relatively unpremeditated manner. In reality, this was not Booth’s first plan to assassinate the president; nor was he acting alone. The assassination of the president was imagined by Booth and his fellow conspirators as a sweeping plot to kill the President, Vice President, and Secretary of State. The plan itself was not well-conceived, and the conspirators’ ultimate aim of reviving Southern military operations was foolish in light of their lack of affiliation with the Confederacy. They merely managed partial success by killing Lincoln and wounding William Seward, and their plot failed to spark any sort of resurgent rebellion.</span>

In the English language, the word "who" is almost always used as a pronoun.
It represents a person, similar to the words "I" and "me".
The correct answer is one is focused on concrete details in the text; the other is focused on ideas more subtly implied by the text
Explicit deals with details directly spoken, while inferential deals with infering, that is, some people incorrectly describe it as "what the author was trying to say".