The answer is to your question my friend is D.
The answer for the above question is Mutation.
Mutations are random spontaneous changes that occur suddenly in the DNA. A single mutation can have a large effect, however in may cases evolutionary changes are based on the accumulation of many mutations. The gene flow is any movement of genes from one generation to another and is an important source of mutation
Not sure what the choices are but a biotic factor is anything living.
