问题如下：
9.Lee’s put-based hedge strategy for Solomon’s ETF position would most likely result in a portfolio gamma that is:
选项：
A. negative.
B. neutral.
C. positive.
解释：
C is correct.
Because the gamma of the stock position is 0 and the put gamma is always non-negative, adding a long position in put options would most likely result in a positive portfolio gamma.
Gamma is the change in delta from a small change in the stock’s value. A stock position always has a delta of +1. Because the delta does not change, gamma equals 0.
The gamma of a call equals the gamma of a similar put, which can be proven using put-call parity.
老师，这道题在题目正文里的表达，long put 是为了hedge larger moves，我的理解就是gamma hedge，我觉得它是接着上面一段说的，delta hedge不仅要用short call，还要同时long put,使得gamma中性，结果选B。不知道哪里出了问题？
