Answer:
A
Explanation:
This line is not talking about his morals, or interests in general. So, from the given answers C and D are off the list from the possible answer. Now, because it says " not unacquainted", it is leaning toward the fact that he had basic or any kind of knowledge beforehand. So, the right answer indeed is A.
It is appropriate for a research paper because it is not opinion based or based in fantasy, it is a real thing you can do research on.
If you want to fix this sentence it would be:
Mom had appreciated our hard work. (Or) Mom appreciated us working so hard.
I can not remember the chapter, but I hope this helps.
The battle of the Five Armies, Smaug attacks Lake-town. He is killed by Bard with an elongated iron arrow and his body falls on the boat carrying the fleeing Master of Lake-town