"Goaf" in relation to Bord & Pillar or L/W working means a place

Goaf Definition:
A goaf is a void or cavity created underground after the extraction of minerals, such as coal, in a Bord and Pillar or Longwall mining method.

Correct Answer: A: Coal has been extracted but now not a working place
Once the coal is extracted in a Bord and Pillar or Longwall system, the area becomes a goaf. It's no longer actively used for mining operations because the coal has already been removed. The goaf is essentially a large, empty space left behind. Safety measures are often implemented to manage the goaf, as it can present risks like roof collapse or gas accumulation.

Why other options are incorrect:
B: Coal has been extracted but still a working place - This is incorrect. A goaf, by definition, is the area where the coal has already been extracted, and thus it is no longer a working place.
C: Coal is about to be extracted - This describes an area ready for mining, not a goaf. A goaf is the space *after* extraction.
D: People has lawful access - While access to a goaf might be permitted under specific circumstances (e.g., for inspections or maintenance), it is not the defining characteristic of a goaf. The primary characteristic is the void created by the removal of extracted material.