Question

sara just found out that her sister conceived about 7 days ago. she rushes to find a book on pregnancy so that she can learn more about it. what will the book say is happening around the seventh day of pregnancy? the cells of the fetus are beginning to differentiate. the cells of the zygote are beginning to differentiate. the embryo has doubled its size. the fetus has tripled its size.

Explanation:

Around 7 days after conception, the zygote has traveled to the uterus and is starting to implant. At this stage, the cells of the zygote begin to differentiate. The term 'fetus' is used later in pregnancy (after 8 - 10 weeks), and there is no mention of size - doubling or tripling at 7 days.

Answer:

The cells of the zygote are beginning to differentiate.