What is a rock and a stone

hope this helps

Explanation:

A rock is a naturally occurring solid. It is made of minerals (which are crystalline), or other mineral-like substances. The Earth's outer solid layer, the lithosphere, is made of rock. That means the Earth's crust is made of rock. The different minerals in the rocks make different kinds of rock.

A calculus (plural calculi), often called a stone, is a concretion of material, usually mineral salts, that forms in an organ or duct of the body. Formation of calculi is known as lithiasis. Stones can cause a number of medical conditions.

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.