It all contains carbon.
Hopefully thats the answer because you didnt put up the choices.
Meiosis. Sexual recombination. Crossing over. Independent assortment. Mutations.
The two MAIN sources would be genetic(sexual) recombination and mutations. Mutations allow for genetic variation, while genetic recombination allows for genetic shuffling. :)
B!!!!!!!!!!!!!!!!!!!!!!!!!!
The correct answer is option C, that is, physical weathering.
The weathering resulting due to the influences of changing temperatures on a rock, making the rock to split apart is known as physical weathering. There are two main kinds of physical weathering, that is, exfoliation and freeze-thaw.
Physical weathering takes place mainly in the locations, where few plants grow and little formation of soil occurs, like hot deserts and mountain regions. It takes place either via repeated freezing and melting of water or via contraction and expansion of the rocks surface layer, which is baked by the sun.
