On October $15,2020,$ the board of directors of Ensor Materials Corporation approved a stock option plan for key executives. On January $1,2021,20$ million stock options were granted, exercisable for $20$ million shares of Ensor's $$1$ par common stock. The options are exercisable between January $1,2024,$ and December $31,2026,$ at $80\%$ of the quoted market price on January $1,2021,$ which was $$15.$ The fair value of the $20$ million options, estimated by an appropriate option pricing model, is $$6$ per option. Ensor chooses the option to recognize forfeitures only when they occur.

Ten percent $(2$ million$)$ of the options were forfeited when an executive resigned in $2022.$ All other options were exercised on July $12,2025,$ when the stock's price jumped unexpectedly to $$19$ per share.

Required:

When is Ensor's stock option measurement date?

Determine the compensation expense for the stock option plan in $2021.($Ignore taxes.$)$

Prepare the journal entries to reflect the effect of forfeiture of the stock options on Ensor's financial statements for $2022$ and $2023.$

Is this effect consistent with the general approach for accounting for changes in estimates? Explain.

Prepare the journal entry to account for the exercise of the options in $2025.$