Which increases genetic variation?

Mutation.

Explanation:

The mutation increase genetic variation.

This mutation can be natural or artificial means man made. In genetic engineering, recombinant DNA technology also used to do mutation. The only mutation can bring significant changes in any organism.

All other processes of genetic variation do not carry as much as variation like mutation.

air, water, heat and noise pollution can all be caused by producing and using technology. consuming resources - non-renewable resources, including precious metals like gold, are used to make technology