Q: Fact 1: Stalactites are formed by deposition. Fact 2: Limestone caves displaying stalactites. Given the two facts above, how are limestone caves formed?

Choose your answer from:
[1]. less water.
[2]. Depositions.
[3]. They're manmade.
[4]. erosion.
[5]. Water expanding.
[6]. Thunderstorms.
[7]. They're made by animals.
[8]. rainfall.
A:
[2].