Final answer:
The supper money received from Perfection Tax Service must be included in the employee's gross income as additional compensation for working overtime.
Step-by-step explanation:
The supper money received from Perfection Tax Service must be included in the employee's gross income. This is because supper money is considered as additional compensation for working overtime, and it is subject to income tax. Therefore, option a. Must be included in the employee's gross income, is the correct answer.