Answer:
A) exon shuffling
Step-by-step explanation:
Exon shuffling refers to the process of evolution of a new gene that consists of unique combinations of preexisting exons. These novel combinations of preexisting exons are formed when the interspersed repeats of introns of two different genes undergo the process of recombination.
The process of exon reshuffling is responsible for the presence of common domains between two otherwise different proteins of eukaryotes.
Example: Tissue plasminogen activator and epidermal growth factor are very different proteins but share the EGF domain.