The simile in "Two Kinds" compares the narrator's "disappointment" to a "prodigy" who has "fallen from grace."
How to explain
This comparison, metaphorically linking disappointment to a failed prodigy, emphasizes the profound disappointment the mother feels in her daughter's perceived failure.
It underscores the weight of the mother's expectations and her shattered hopes for her daughter's success.
Therefore, the effect of the simile is best described as option C: it showcases the narrator's awareness of the depth of her mother's hurt and the impact of her words on her mother's disappointment and dashed aspirations.