The correct answer is A. 200 meters.
LPG is a highly flammable gas. If there is a leakage in an LPG tank wagon, the surrounding area may be sealed from fire to prevent an explosion. The area that needs to be sealed depends on the size of the leak and the type of LPG. For a small leak, the area may only need to be sealed for a few meters. However, for a large leak, the area may need to be sealed for up to 200 meters.
Option B is incorrect because it is too large. Option C is incorrect because it is too small. Option D is incorrect because it is not a valid option.