The NBBO for ACME common stock is 500 shares bid for at $52.30 and 600 shares offered at $52.42. The probability that a limit order to purchase 800 shares at a price of $52.42 is filled when it arrives in the marketplace is the probability that a limit order to purchase 800 shares at a price of $52.45 is filled when it arrives in the marketplace. Note: Assume both scenarios are independent and either one or the other can occur. a. lower than O b. the same as O higher than O d. impossible to tell