on January 1, 2021, D corp. granted an employee an option to purchase 6000 shares of D's $1 par common stock at $20 per share. The options became exercisable on December 31, 2022, after the employee completed two years of service (i.e. the service period). The option was exercised on January 10, 2023. The market prices of D's stock were as follows: January 1 of 2021, $26; December 31, 2022, $50; and January 10, 2023, $45. an option pricing model estimated the value of the options at $8 each on the granted date. For 2021, D should recognize compensation expense of: