The answer is b because it gives both takes on the topic in hand.
This passage uses personification. Words cannot actually be stiff or heavy, and they do not need to be pushed out of one's mouth, but these adjectives and actions give the reader a vivid picture of Molly trying to say this words, and struggling greatly to do so.
You need to put more space in it this is to hard to read
Like something you have experienced personally…
Hope this helps
