Final answer:
The incorrect statement regarding Trisomy 21 is that it occurs in 1 out of 10,000 births. The actual frequency is about 1 out of 700 births.
Step-by-step explanation:
The statement 'Trisomy 21 occurs in 1 out of 10,000 births' is incorrect. Trisomy 21, or Down syndrome, is indeed caused by having three copies of chromosome 21 (hence, 'trisomy') and is a result of nondisjunction during meiosis. An individual with Down syndrome has some degree of mental and physical impairments, but paralysis of limbs is not typically associated with this condition. The actual incidence of Down syndrome is higher; it occurs in approximately 1 out of 700 births. Additionally, Trisomy 21 is compatible with life into adulthood, making choice 'a' correct. The incorrect number of chromosomes in a person with Trisomy 21 leads to a variety of symptoms, including characteristic facial features, developmental delays, and potential for a range of health issues, but not generally paralysis.