Add(s) genetic variation, which is essential for evolution.

natural selection
mutations
hardy-weinberg conditions
genetic drift
migration

The answer is Mutations.

Mutation are the alteration of a nucleotide sequence in DNA. By changing a DNA sequence, the mutations produce new sequences, and consequently the mutations add genetic variation. On the other hand, natural selection takes them away. Genetic drift and migration decrease genetic variation because of the random sampling and migrating of only some individuals, respectively. Likewise, in the Hardy-Weinberg conditions there must be no mutations.

The scientific method is a series of steps followed by scientific investigators to answer specific questions about the natural world. it involves making observations, formulating a hypothesis, and conducting scientific experiments.the steps of the scientific method are •observation-the first step of the scientific method involves making an observation about something that interests you•question-once you've made your observation, you must formulate a question about what you have observed. •hypothesis-once you've made your observation, you must formulate a question about what you have observed. •experiment-once you've developed a hypothesis, you must design and conduct an experiment that will test it.•results-the results are where you report what happened in the experiment. •conclusion-the final step of the scientific method is developing a conclusion.i hope that this you : )