The recovery of pillars in room and pillar mining is called:

Solution (By Examveda Team)

Room and Pillar Mining:
Room and pillar mining is a mining method where ore is extracted by creating a grid of rooms separated by pillars of ore. These pillars support the overlying rock and prevent cave-ins. After the rooms are mined, the pillars may be subsequently extracted, depending on the stability of the ground and mining goals. This subsequent extraction of the pillars is the key to understanding the question.

Retreat Mining:
Retreat mining is the correct answer. In retreat mining, the rooms are initially mined leaving the pillars in place. These pillars then provide support for the overlying strata. Once mining in a section is complete, the pillars are systematically removed in a planned retreat, allowing the overlying ground to subside in a controlled manner. This controlled subsidence is important for ground stability and safety.

Why other options are incorrect:
Primary Stoping: This is a method of underground mining typically used in steeply dipping orebodies, not related to room and pillar techniques.
Forward Mining: This involves mining in a continuous advance, typically without leaving pillars for later extraction. It's opposite to retreat mining.
Sublevel Mining: This method involves creating a series of horizontal sublevels in an orebody, it does not involve the room and pillar layout and pillar extraction characteristic of this question.