The excess of DNA is due to b. insertion
For example of an insertion mutation:
The Klinefelter syndrome is caused by an insertion mutation. It occurs when there is an existence of an excess or extra X chromosome in each cell that may cause an abnormality in the development of males. It usually affects the physical and cognitive development of male with symptoms varying from one person to another. Kids with these type of disorder may experience learning disabilities and even speech and language problems. These kids tend to be quiet and very sensitive. They can also be very passive.