On October 15, 2015, the board of directors of Ensor Materials Corporation approved a stock option plan for key executives. On January 1, 2016, 20 million stock options were granted, exercisable for 20 million shares of Ensor's $1 par common stock. The options are exercisable between January 1, 2019, and December 31, 2021, at 80% of the quoted market price on January 1, 2016, which was $15. The fair value of the 20 million options, estimated by an appropriate option pricing model, is $3 per option.

2 million options were forfeited when an executive resigned in 2017. All other options were exercised on July 12, 2020, when the stock's price jumped unexpectedly to $39 per share.

When is Ensors stock option measurement date?

Determine the compensation expense for the stock option plan in 2016. (Ignore taxes.)

Prepare the necessary journal entries.

Record compensation expense on December 31, 2017.

Record compensation expensive on December 31, 2018.

Record the exercise of the options in 2020.