During the 7th Month of Pregnancy, a Woman Notices a Yellowish

During the 7th month of pregnancy, a woman notices a yellowish discharge from her nipple. Which is the best explanation for this discharge?

A) An infection is present.
B) This is witch's milk, caused by elevated estrogen levels.
C) This is breast milk, and delivery is imminent.
D) Colostrum is secreted in preparation for milk production.