Both are great ways to help improve your vocabulary and spelling. However I would suggest frequent reading to familiarize yourself with the words.
Answer:
Marilla grows anxious.
Explanation:
Here in the story: "Thereupon Anne held her tongue so obediently and thoroughly that her continued silence made Marilla rather nervous, as if in the presence of something not exactly natural.", shows that Marilla grows nervous when Anne didn't talk.
