Recall the investment option in Example 63 in which a customer may purchase a unit of a stock at a price K at time T . Consider this option with the additional stipulation that the customer “must”...

Recall the investment option in Example 63 in which a customer may purchase a unit of a stock at a price K at time T . Consider this option with the additional stipulation that the customer “must” purchase a unit of the stock before time T if its price reaches a prescribed level a, and consequently the other purchase at time T is not allowed. In this setting, the customer must purchase the stock at the price a prior to time t, if maxx≤t X(s) = eM(t) > a, where M(t) = maxs≤t B(s). Otherwise, the option of a purchase at the price K is still available at time T . In this case, the value of the option isExample 63