Answer:
B. He realizes the gift he bought her is useless now.
Explanation:
In "The Gift of the Magi," we learn that Della cut her hair short in order to get a present for Jim. However, Jim's gift was dependant on Della's long hair. When he realizes that she has cut her hair, Jim is shocked. However, the shock is not only because of how different she looks, but also because he realizes that the gift is useless now.