When a Blood Test Was Performed on Cindy's Fetus,the Doctors

Multiple Choice

When a blood test was performed on Cindy's fetus,the doctors found some of Cindy's red blood cells in the fetus's circulatory system.We know that this

A) is normal because the mother is the source of red blood cells for the fetus.
B) is normal because the mother's red blood cells are a source of oxygen for the fetus.
C) indicates a problem with the placenta,which should block the mother's red blood cells.
D) indicates a problem with the amnion,which should eliminate the mother's red blood cells.