Is it possible to first evaluate OVT and then discount this to time 0 to give OV, rather than discounting E[ST] and Var[ST] to time 0, and then evaluating OV? Would you anticipate that you would get the same answers either way that you did the calculation? Is OV the same as a discounted OVT? If not, what is the difference and why is there a difference? Test this numerically. Try a range of values of ST, K, r and T. Compare OV calculated by both approaches.