What are the 3 main mechanisms responsible for genetic variation

What can be said about farmers in highly developed countries? a) they have little or no negative impact on the environment. b) they practice subsistence agriculture. c) they are able to incorporate polyculture into their farming practices. d) they utilize organic farming techniques on a regular basis. e) they rely on large amounts of energy from fossil fuels.

When a gasoline engine burns gasoline, what type of chemical reaction is occurring?

Can a trait be both polygenic and have multiple alleles? explain why or why not.