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?

a. Buy 65,000 shares

b. Buy 100,000 shares

c. Buy 21,000 shares

d. Sell 100,000 shares

DO NOT COPY OR ELSE I WILL REPORT, ALSO I NEED FULL CALCULATION STEP BY STEP.