A 2-day-old infant has significant jaundice. The pregnancy was without complications. His Apgar scores were 8 at 1 minute and 9 at 5 minutes. He has breastfed well and has not required a health care professional visit since birth. Which of the following vitamin deficiencies might explain his condition?

a. Vitamin A
b. Vitamin B1
c. Vitamin D
d. Vitamin K