Final answer:
Option (C), Compensation from restricted stock is taxable when the risk of forfeiture ends, which is typically when the stock vests.
Step-by-step explanation:
When an employer (ER) compensates an employee (EE) with restricted stock, the compensation is taxable when the risk of forfeiture ends. This event is known as vesting. At this point, the employee has earned the right to the stock, and it cannot be taken away under the terms of the vesting schedule. This means the correct answer is C) When the risk of forfeiture ends. The income recognized is typically the fair market value of the stock at the time it vests, and this is what will be included in the employee's taxable income for that year.