In a Typical Site- Cast Reinforced- Concrete Structure, the Cost

In a typical site- cast reinforced- concrete structure, the cost of formwork and shores is

A) approximately 50% of the combined cost of concrete and steel.
B) approximately 75% of the combined cost of concrete and steel.
C) approximately equal to the combined cost of concrete and steel.
D) approximately 25% of the combined cost of concrete and steel.
E) none of the above.