Walker, Incorporated uses stock options as a compensation incentive for its top executives. On January 1, Year 1, 25,000 options were granted, each giving the holder the right to acquire one $5 par common share. The exercise price is $60 per share. The vesting period is 4 years. Options vest on January 1, Year 5 and cannot be exercised before that date and will expire on December 31, Year 8. The fair value of the 25,000 options, estimated by an appropriate option pricing model is $50 per option. a. Make the journal entries to record compensation expense for Year 1. b. On April 1, Year 7, when the market price of Walker's stock was $20 per share, 15,000 of the options were exercised. Make the appropriate journal entry to record this transaction. c. Assuming that all compensation expense has been recorded, record the journal entry to reflect the expiration of 3,000 options that were never exercised