Emmanuel exercised a nonstatutory stock option on March 14, 2021. He purchased 200 shares of his company's stock for $6,000. The fair market value of the stock at the time of purchase was $8,000. He included the $2,000 difference between the fair market value and the purchase price as compensation income when he filed his 2021 return. What is Emmanuel's basis in the underlying stock?

$0

$2,000

$6,000

$8,000