The correct combination of stalactite and stalagmite occurrences is provided in option 2: "Stalactites hang as icicles of different diameters and stalagmites rise up from the floor of the caves."

To understand this combination, let`s break it down:

- Stalactites: These formations hang from the ceiling of caves and are formed when mineral-rich water drips down and leaves behind deposits of minerals. They usually have a conical or cylindrical shape and can vary in diameter.

- Stalagmites: These formations rise up from the floor of caves and are formed when mineral-rich water drips onto the floor and builds up over time. They also have a conical or cylindrical shape and can vary in height.

So, in option 2, both stalactites and stalagmites are described correctly in terms of their appearance and location. Stalactites hang from the ceiling like icicles, while stalagmites rise up from the cave floor.

It is important to note that the option correctly describes the difference in location between stalactites and stalagmites. Stalactites hang from the ceiling, while stalagmites rise up from the floor. This combination accurately reflects the natural occurrence of these formations in caves.