Fossil records are important for understanding change in living organism however there are multiple limitations including ( choose all that apply )
1. evolutionary trends in fossils may change when new fossils are found
2. some organisms do not create fossils
3. fossil records are biased towards certain types of species
4. not all fossils have been found

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

glacial erosion, the picking up and movement of earth beneath a glacier, is also referred to as plucking. erosion and transportation of individual pieces of bedrock, especially large "joint block occur as a result of this glacial erosion. plucking is type of erosion in which rocks become frozen into the bottom and sides of the glacier.as the glacier moves downhill it 'plucks' the rocks frozen into the glacier from the ground.

d. planting trees

the trees take in carbon to make oxygen.