Down;s syndrome is also known as trisomy 21 because it is caused by an additional copy of chromosome 21. The correct answer is the third one: 21st.
B because a and c are incorrect and in letter d it states earth has no protection at all. And it DOES have protection B is most definitely true
East coast , west coast, and Gulf of new mexico...Please mark me the Brainliest! thank you!!
To name one of many:
If Ben's car will not start, then the battery may be dead.
