Which of the Following Statements Is True of Down's Syndrome

Multiple Choice

Which of the following statements is true of Down's syndrome?

A) Down's syndrome is usually caused by a defect in the sex chromosomes of an individual.
B) The symptoms of Down's syndrome are similar to those of sickle-cell anemia.
C) Down's syndrome is caused by a sexually transmitted infection (STI) during conception.
D) The probability of having a child with Down's syndrome increases with the age of the parents.