On October 15, 2015, the board of directors of Ensor Materials Corporation approved a stock option plan for key executives. On January 1, 2016, 26 million stock options were granted, exercisable for 26 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 $20. The fair value of the 26 million options, estimated by an appropriate option pricing model, is $6 per option. 2.6 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 $25 per share

1When is Ensors stock option measurement date?

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

Record the exercise of the options in 2020.

3&5) Prepare the necessary journal entries

Record compensation expense on December 31, 2017

Record compensation expense on December 31, 2018

Record the exercise of the options in 2020.