The answer is not d. The correct answer should be B.
Explanation:
If I'm wrong please tell me .Also please do not use the answer option to ask a question, it is a waste and there is a place to ask questions without using it.
You give a tip as a gratuity for their service of helping you and by the choice of how much is given to the worker it can say if they really deserved the tip by giving them 20% but if it was just another day at this place you’ll probably just give them a 10% tip.