Estimating and Costing - Engineering

Q1:

While estimating a reinforced cement structure, the omitted cover of concrete is assumed

A at the end of reminforcing bar, not less than 25 mm or twice the diameter of the bar

B in thin slabs, 12 mm minimum or diameter of the bar whichever is more

C for reinforcing longitudinal bar in a beam 25 mm minimum or diameter of the largest bar which is more

D All the above.

ANS:D - All the above.

Please tell me where to find these type of information? Is there any code available?