Help 10 points!! Underground limestone caves form?

Question

which one

when calcite is dissolved by carbonic acid in rainwater

from compacting and cementing weathered rock fragments so they contract

when oxidation decomposes minerals in the rock

when cooling magma contracts

Answer 1

A

Answer 2

Rainwater can dissolve calcite. It has picked up carbon dioxide from the air and soil and turns the limestone into calcium bicarbonate. Then calcium carbonate (limestone) forms when the solution is deposited, either through evaporation or by impact.