According to I.S. : 456 specifications, the safe diagonal tensile stress for M 150 grade concrete, is A. 5 kg/cm2 B. 10 kg/cm2 C. 15 kg/cm2 D. 20 kg/cm2

The correct answer is: B. 10 kg/cm2

The safe diagonal tensile stress for M 150 grade concrete is 10 kg/cm2. This means that the concrete can withstand a tensile stress of up to 10 kg/cm2 before it fails.

The other options are incorrect. Option A is too low, and option C and D are too high.

The safe diagonal tensile stress is an important factor to consider when designing concrete structures. It is important to ensure that the concrete is strong enough to withstand the tensile stresses that it will be subjected to.