Why is one side of the moon called "the dark side of the moon"
a. the moon both rotates on its axis and revolves around earth every 28 days.
b. the moon is in earth's shadow
c. earth is in the moon's shadow

Which of the following is an advantage of using embryonic stem cells in medical research? a. the use of embryonic stem cells is much less expensive than the use of adult stem cells. o b. no living tissue is damaged when scientists use embryonic stem cells. o c. embryonic stem cells are able to differentiate into a wider range of cells than adult stem cells. d. there is no controversy surrounding the use of embryonic stem cells.