Reva is employed by Clean Air, Inc. Clean Air grants Reva the option to purchase 1,000 shares of its stock when it is selling for \($135\) per share on March 10, Year 2.

The exercise price is \($150\) per share. Reva exercises her option on December 10, Year 3 when the price is \($165.\) She sells her 1,000 shares on April 15, Year 4.

Identify the key dates for these transactions.