问一道题：NO.PZ2016082404000028

NO.PZ2016082404000028问题如下You are given the following information about a Europecall option: Time to maturity = 2 years; continuous risk-free rate = 4%; continuous vinyiel= 1%; N()=0.64N{(1)}=0.64N(​)=0.64 . Calculate the lta of this option.  -0.64   0.36   0.63   0.64 ANSWER: CThis is a call option, so lta must positive. This is given △=e-r∗τN()=e−0.01×2×0.64=0.63.\bigtriangleup\text{=}e^{\text{-}r\ast\tau}N{(1)}=e^{-0.01\times2}\times0.64=0.63.△=e-r∗τN(​)=e−0.01×2×0.64=0.63.上一题lta不用乘以N(),这一题为什么要乘？

在计算N （）的时候就已经把S替换为剔除了分红的价格，lta call＝N （），为什么在算lta call的时候还要再剔除一次分红呢？