NO.PZ2023091802000145
问题如下：
A bank has sold USD 300,000 of call options on 100,000 equities. The equities trade at 50, the option strike price is 49, the maturity is in three months, volatility is 20%, and the interest rate is 5%. How does the bank delta-hedge?
选项：
A.Buy 65,000 shares.
B.Buy 100,000 shares.
C.Buy 21,000 shares.
D.Sell 100,000 shares.
解释：
This is an at-the-money option with a delta of about 0.5. Since the
bank sold calls, it needs to delta-hedge by buying the shares. With a delta of
0.54, it would need to buy approximately 50,000 shares. Answer A is the
closest. Note that most other information is superfluous.
请问能提供一下计算Delta的过程么？
