Why can diamonds form in the mantle? a. the weight of the rocks in the outer core increases the temperature. b. the sun and moon cause a low pressure in the upper mantle. c. the weight of the rocks in the outer core results in high pressure. d. the weight of the rocks above the mantle results in high pressure

Diamonds cam form in the mantle because of the impact of the weight of the overlying rock which bears down on it, in combination with the high temperature of the area where they are formed (about 100 miles beneath the surface). Therefore,  the correct answer is option D. The weight of the rocks above the mantle results in high pressure.

Answerwill have thinner; have thicker oceanic sediments;

The answer is a. it makes more sense then the other answers listed there.