I would go with barb, think of a barbed wire fence and then think of the tip of the arrow. It makes the best match.
The answer is indeed (B) adverb phrase
1 = whereas
2 = right
3 = background
4 = decreased
5 = cope
6 = came
7 = had
8 = disturbed
9 = presented
10 = task
11 = line
12 = particularly
hope this helps you
The represent that the shape of the wall was a portent.
