What is the main mechanism by which rocks in the upper part of earth's crust melt?

Intrusion of magma

Explanation:

The main mechanism by which the rocks in the upper part of the earth's crust melt is known as the intrusion of magma. The intrusion of magma is any formation of intrusive igneous rock. The rock is formed from magma that cools and solidifies within the crust of the planet. This results in formations called lacoliths that are trapped beneath the surface of the earth and push the rock above it to form a dome shape.

some fungi obtain their nutrients from a living host (plant or animal) and are called most biotrophic fungi have fairly narrow host ranges—they are specialized on a limited called rhizomorphs that allow the fungus to grow from one tree to another. ascospores are formed inside a sac-like structure called an ascus. so your answer is a