The spot price of the market index is $900. A 3-month forward contract on this index is priced at $930. The market index rises to $920 by the expiration date. The annual rate of interest on treasuries is 4.8% (0.4% per month). What is the difference in the payoffs between a long index investment and a long forward contract investment? (Assume monthly compounding)
A. $19.16
B. $26.40
C. $43.20
D. $10.84