<span>B is the correct answer. The beginning of DNA replication occurs with the unwinding of the DNA helix by a special enzyme. The two strands that form the helix then create a replication fork. The two strands are then oriented differently, one becoming the 'leading strand' and one the 'lagging strand'. </span>
The cause of mutations in gene expressions are the changes of gene instructions that causes your protein to malfunction. The effect of mutations are the genes not being able to function properly and send the wrong codes/info to your cells.