Concept:Limestone cave formations are identified by their direction of growth — from the floor or from the ceiling.
Explanation:The given description refers to a pinnacle of calcium that grows from the floor of a limestone cave.
This type of formation is known as a stalagmite.
A stalagmite builds upward from the cave floor as mineral-rich water drips down and deposits calcium carbonate.
In contrast, a stalactite hangs downward from the cave ceiling.
A clint is a flat block on a limestone pavement, while a stump is a marine erosion feature.
Therefore, the phrase "grows from the floor" clearly matches a stalagmite.
Answer:B. stalagmite