What does the author mean when he writes that Della's "face had lost its colour"?

7) Suddenly she whirled from the window and stood before the glass. Her eyes were shining brilliantly, but her face had lost its colour within twenty seconds. Rapidly she pulled down her hair and let it fall to its full length.

A.
Della's hair is her only element of beauty.
B.
Della has realized what she must give up for Jim.
C.
Della has become sick with worry about Jim's gift.
D.
Della's complexion is fair and exquisite.