Which of the following is least likely to be assessable income of an apprentice restaurant chef? A. An overtime payment of $120 for working over the Easter holiday weekend. B. A $500 cash bonus given to all employees at the end of the year by their employer in appreciation of their efforts. C. A reimbursement of $364 from their employer for the costs of textbooks purchased by the trainee for their apprenticeship course. D. A gratuity (tip) left by an anonymous restaurant customer in appreciation of the meal they received from the apprentice. E. All of the above are assessable.