This is caused by trisomy 21 (a nondisjunction), causing highly variable degrees of learning difficulties and physical disabilities.

1) a

2)c

3)a

4)c

5)b

hope this , if so, your appreciation would be signified through giving   me brainliest, and a you : ) have any further questions? feel   free to ask me in the questions box.

it’s

explanation:

answer; lower are;