What are stalactites?

Stalactites are found in limestone caves. They occur as a pair with a stalagmite. As water that contains acid drips from the roof of the cave if dissolves some of the limestone and drips to the floor. As the water drips, the stalactite is formed from the roof of the cave and the corresponding stalagmite form below as the water drips onto the floor.

Answer(a); // soil salinization and waterlogging;