Alex has been employed by a Canadian private corporation for many years now.To recognise his contribution to the company, on January 1, 2017, Alex was granted the option to buy 1,000 shares of his employer's common shares at a price of $25.00 per share.At that time, the shares were worth $27.00 each.On June 1, 2018, Alex exercised his option and acquired 1,000 shares at $25 each.At that time, the shares were worth $42.00 each. Alex sold all the 1,000 shares on May 1, 2020 for proceeds of $50.00 per share.

Which of the following answers corresponds to the stock option benefit to be included in Alex's Net Employment Income for the year 2020?

$8,500

$25,000

$21,000

$17,000

$4,000

$12,500