Is there a picture to go with this?
Carbon dioxide, oxygen, water, and acids may all cause chemical weathering. Mechanical weathering is the process of breaking a large rock into smaller pieces without changing the minerals in the rock. Mechanical weathering may be caused by frost, ice, plant roots, running water, or heat from the sun.
An ecological niche is an organism's specific habitat in an ecosystem.
It is where it lives and feeds, etc.
I think the correct answer from the choices listed above is option A. For metamorphism to occur, the parent rock must be in solid form. Metamorphism is the alteration of the structure of a rock by factors like heat and temperature so it must be the material should be in solid form.