The correct answer is: A. 2 to 3 t/m2
Black cotton soil is a type of soil that is found in many parts of India. It is a very heavy soil that is high in organic matter. This makes it very difficult to work with and it has a low bearing capacity. This means that it can only support a small amount of weight before it starts to sink.
The safe bearing capacity of black cotton soil is typically between 2 and 3 t/m2. This means that a foundation on black cotton soil can only support a load of up to 3 tonnes per square metre. If the load is too heavy, the soil will start to sink and the foundation will become unstable.
It is important to take the safe bearing capacity of black cotton soil into account when designing any type of structure that is going to be built on it. If the safe bearing capacity is not taken into account, the structure could collapse.
The other options are incorrect because they are too high. Black cotton soil is a very weak soil and it cannot support a large amount of weight.