Stalactites and Stalagmites are both cave formations. They are formed from water dripping and dropping mineral deposits inside a cave or its tunnels. Stalactites (with a c) seem to hang down from the ceiling while stalagmites (with a g) seem to grow up from the ground. In fact, stalagmites do not grow up from the ground but rather are created by the minerals dropping from the ceiling and landing in the same place so as to cause an accumulation.
The correct answer is C. types of cave formations.
Stalactites and stalagmite are both types of cave formations but stalactites are formed from dripping water from the ceilings or the walls and have an icicle-like shape pointing downward toward the floor. While the stalagmites have a mound like-shape and points upward toward the ceiling.
