example 16.5: FRM EXAM 2004
in early 2000, a risk manager calculates the VAR for a technology stock fund based on the past three years of data. the stratege of the fund is to buy stocks and write out-of-the-money puts. the manager needs to compute VAR. which of the following methods would yield results that are least representative of the risks inherent in the portfolio?
a...
b. delta-normal VAR assuming zero drift
c...
d. historical simulation using delta equivalents for all postions

选d
a,c 排出就不列出来了，可是b为什么不选？

求各位高手帮忙解读下