12. Option Valuation. Table 23-2 shows call options on Google stock with the same exercise date in March and with exercise prices $620, $720, and $820. Notice that the price of the middle call option (with exercise price $720) is less than halfway between the prices of the other two calls (with exercise prices $620 and $820). Suppose that this were not the case. For example, suppose that the price of the middle call were the average of the prices of the other two calls. Show that if you sell two of the middle calls and use the proceeds to buy one each of the other calls, your proceeds in March may be positive but cannot be negative despite the fact that your net outlay today is zero. What can you deduce from this example about option pricing? (LO2)