问题如下：
Hill refers his friend, Richard Morrison, the former CEO of Masury Bridge and Iron (MBI), to Keller to discuss his wealth goals.
Keller realizes that the Morrisons’ decision making is influenced by psychological considerations and decides to use a goal-based planning approach. Keller constructs the table below to simplify the discussion at their next scheduled meeting.
Table：Morrison Family Wealth Distribution
Keller and Richard Morrison discuss several hedging techniques and Morrison makes the following statement:
"I like the strategy that allows me to lock-in a floor price and retain unlimited upside potential."
Identify and discuss the hedging tool that Morrison is most likely referring to in the above statement.
选项： 解释：
The hedging tool Morrison is most likely describing is a protective put position. The strategy is the combination of a long stock position and a long put position, which would provide downside protection (lock in a floor price) with unlimited upside participation. Morrison would buy put options equivalent to the number of shares to be hedged. The put options would have a strike price that is either at or, more typically, slightly below the current stock price. Morrison would pay an amount, referred to as the option premium, to acquire the puts. Conceptually, this is similar to the payment of an insurance premium. If the price of MBI falls below the strike price during the term of the option, the put option could be exercised at the strike price, providing downside protection. If the share price is above the strike price at maturity, Morrison would let the option expire and retain the upside.
A zero-premium collar would not accomplish Morrison’s goal to lock in a floor price and retain unlimited upside potential. A cashless collar is established by buying puts and selling calls on the shares to be hedged. The long put protects the owner of the shares from any loss below the strike price of the puts. However, the investor forfeits some of the upside potential of the underlying stock. Like a cashless collar, a prepaid variable forward (PVF) would not accomplish Morrison’s goal. A PVF combines the economics of a collar and borrowing against the underlying stock within a single instrument.
这道题直接回答purchase put用来hedge downside risk，同时在股价上升的时候put不行权，所以有unlimited gain就可以了吧？
