Which is a likely explanation for why there are no data included on the graph for maternal ages above 45?
a) In women over 45, the incidence of Down syndrome is confounded by other genetic disorders.
b) Because women of younger ages are more open to giving data than older women.
c) Because the number of births to women older than 45 is much smaller than births to younger women.
d) Above 45, the incidence of Down syndrome approaches 100%.
e) Women over the age of 45 are not able to give birth.
Answer: c) Because the number of births to women older than 45 is much smaller than births to younger women.