Why does the author include the phrases "the thicker her silences” and "No prodding will elicit clues”? to develop a mood of carelessness, as Obasan is uninterested in the past

to develop a mood of calm, as Obasan is quiet and moves about slowly

to develop a mood of helplessness, as Nomi is frustrated with Obasan’s failure to respond to her

to develop a mood of anger, as Nomi needs Obasan to help her understand the letters’ contents