The answer is B) It suggest a tone of worry. The reason is because the phrase "knitting their cheeks" means the that the llamas were moving their jaws. This along with the fact that they were contemplating the writer suggests that the llamas are unsure of the writer.
I'm not sure but here's the definition of Parallel Structure. ( Using the same pattern of words to show that two or more ideas have the same level of importance). You can go with either the first or second sentence that's my opinion but I'm really not 100% sure. Sorry I couldn't been more helpful. I tried
Something that annoys you to no end, something minor
