What Is the Option Value of Waiting

What is the option value of waiting?

A) the increase in the net present value from postponing an investment until uncertainty about the investment returns is reduced
B) the use of a risk-free discount rate for the evaluation of risky investments
C) the difference between the present discounted value calculated from using the nominal interest rate and the real interest rate
D) the interest rate that causes the net present value of an investment to equal zero