Any condition in an experiment that can be changed?

What part of the brain is highlighted in the diagram below?

Agene pool: a) is the collection of all the alleles found in a single species b) is the collection of all the alleles found in a single population c) is the collection of all the chromosomes found in a single population d) is the collection of genes in a species that allow the individuals to swim

Explain the process that creates the heat of the sun?