Chromosomal abnormalities can be of 3 types:
1. Numerical.
2. Balanced structural.
3. Unbalanced structural.
Structural chromosome abnormalities occur when a piece of an individual chromosome breaks off and relocates in some other way. In unbalanced structural chromosome abnormalities, there is extra or missing information on a chromosome. This last type of anomaly includes duplications, and deletions, among others. In duplications, part of a chromosome is copied or a part of the chromosome is duplicated.
For example, according to the problem, a DNA segment is changed from AATTAG- to -AATTTTAG. Notice that there is an additional fragment: TT in the last sequence.
We can conclude that the correct answer is:
Answer:A. duplication
