C. who or what the passage is about
Taking a position in an argument means taking a side. When taking a side in an argument, the author will most likely give you biased evidence. They will only give you reason to believe their side, without giving you any sort of evidence for the other side in the argument.
I hope this helps!
Tell him to report this to a trusted adult and to not make a big scene of it to the bully just ignore him and not get the reaction the bully wants