What are my the two main sources of genetic variation

Which would best keep the oxygen cycle stable? a. cutting down jungles to create farmland b. eliminating parks in large cities c. dumping toxic chemicals into the ocean d. reducing the amount of deforestation d. reducing the amount of deforestation

Other than earth, is also known to have magnetic pole reversal? a: venus b: mars c: earths moon d: the sun

If an organ has six haploid chromosomes,how many chromosomes are present. 6 12