ABC Corporation awarded John 1,000 options in 2013; each option allows him to purchase one share of ABC Corporation stock for $20. The ABC stock was selling for $18 per share at the grant date. In 2015, John exercised the options when the stocks selling price was $40 per share. In 2017, John sells the stock for $50 per share. How much gain does John recognize in 2017 when he sells the stock if they are incentive stock options? a. $10,000 b. $30,000 c. $0 d. $20,000