Tdivergent plate boundaries in the ocean, magma rises and melts because of intrusive plutons at the boundary increased silica content of magma higher temperatures at the surface a decrease in pressure

a decrease in pressure

Explanation:

A Divergent Limit occurs with the tectonic plates moving away in opposite directions and directions, so there is addition of magmatic material to the Earth's crust at this point. Magma ascends through a space that exists between the plates, called Rifte. At the divergent boundaries of the plates in the ocean, magma rises and melts because of a decrease in pressure caused by the removal of these plates.

dna is made up of six smaller molecules -- a five carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases (adenine, thymine, cytosine and guanine).