The minimum thickness of a load-bearing RCC wall should be 150 mm. This is because the wall needs to be strong enough to support the weight of the structure above it. If the wall is too thin, it may not be able to support the weight and could collapse.
Option A: 50 mm is too thin for a load-bearing wall. It would not be strong enough to support the weight of the structure above it.
Option B: 100 mm is the minimum thickness for a non-load-bearing wall. It is not strong enough to support the weight of a structure above it.
Option C: 150 mm is the minimum thickness for a load-bearing wall. It is strong enough to support the weight of a structure above it.
Option D: 200 mm is the maximum thickness for a load-bearing wall. It is not necessary to make the wall thicker than this, as it will not make it any stronger.