Allosomic trisomy condition is seen in

Sometimes,the presence of $XX$ and $XY$ in males is due to:

What is the number of Barr bodies in a male with Jacobs syndrome?

Feminized males have . . . . . . chromosomes.

Given below are two statements :
Statement $I$ : Down's syndrome is caused by the absence of one of the $X$-chromosomes.
Statement $II$ : Turner's syndrome is caused by the presence of an additional copy of the chromosomes.
In the light of the above statements, choose the correct answer from the options given below :

Which of the following is an example of a non-Mendelian disorder?