The answer is mitochondria
As DNA replication begins the DNA molecule is broken apart into two complementary strands. DNA replication is the process by which DNA makes a copy of itself during cell division. The process occurs in all living and is the basis for biological inheritance. The process starts with the separation of DNA strands in the double helix. Then replication for is formed followed by the binding of bases to each strand. Then the last step is termination of the Replication process
Variation means difference in genetic makeup between individuals within a specie.
