Deletion because it worse then a substitution since your deleting something
Answer: Option C
Explanation:
Edward syndrome is also called as trisomy which is a genetic disorder. This disorder is caused due to the third copy of the all the part of the chromosome number 18.
The babies that are born is small and have heart defects. They have overlapping fingers.
The ultrasound cannot detect the problem but the process of amniocentesis can confirm the syndrome.
I'm pretty sure it is "c"