Fact 1: Acavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone. Fact 2: Erosion by acid solutions is only one way that caves form. Given the two facts above, how are caves formed?

Options: a. less water. b. eruptions. c. Water expanding. d. storing water. e. volcanoes. f. by humans. g. chemical erosion. h. hard outer covering.
Answer:
g.