In a scientific experiment how many independent variables should be tested at the same time

Which statement describes john tuzo wilson’s contribution to the theory of plate tectonics?

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

What molecule does hemoglobin decay into over time