7.C This implies a stock price decrease of $1 leads to option price increase of $0.408247 I dont understand this answer. Why the stock price decrease, option price increases?

7. Let the standard deviation of the continuously compounded return on the stock is 21 percent. Ignore dividends. Respond to the following: a. What is the theoretical fair value of the October 165 call? Calculate this answer by hand and then recalculate it using BSMbin9e.xls. b. Based on your answer in part a, recommend a riskless strategy. c. If the stock price decreases by $1, how will the option position offset the loss on the stock? 8. Use the Black-Scholes-Merton European put option pricing formula for the October 165 put option. Repeat parts a,b, and c of the previous problem with respect to the put