What are the mobile genetic elements called ?

Transposons.

The correct answer is Option (1) –Transposons.

Transposons, also known as "jumping genes," are mobile genetic elements that can move from one location to another within a genome. Transposons can change positions on chromosomes, which can lead to mutations, changes in gene expression, and genome rearrangements. They are important in genetic diversity and evolution.

Transposons work by copying and inserting themselves into new positions within the genome, or they may directly "cut" and "paste" themselves into different locations.