Gimble Inc. granted stock options to its key employees. The options vesting after a 3-year service period and had a total grant-date fair value of $900. During the second year of the service period, several employees left the company and thereby forfeited options with an original total grant-date fair value of $150. What is the total option-related compensation expense that would be reported by Gimble in the first two years of the service period?

First year Second year

a)$ 300 $ 300

b)300 200

c)250 250

d) 900 -0-

e)300 250

On the answer key it says the answer is b) $300 for 1st year and $200 for 2nd year but I don't how how it got that answer. Can someone to me how? Show your work please! thanks in advance!