Answer:
B. Fixed ratio
Explanation:
Fixed ratio schedule is a type of schedule reinforcement where response is reinforced after only a specific number of response. In this case, a response of $10 bonus is reinforced after only they write twenty (20) tickets (specific number of response).
They are those in which a response is reinforced only after a specified number of responses. The idea is that, the worker produces a agreed upon number of responses with the manager or owners. And when he reaches that number of responses, he's offered his reward in bonuses.