Answer:
C) variable-interval schedule
Explanation:
Based on the scenario being described within the question it can be said that Daniel's watching behavior is likely to be reinforced based on a variable-interval schedule. This schedule refers to when the reward is given after a random amount of time has passed, which is not predictable. In this case seeing since Daniel does not know when the ducks will pass but knows that they will pass, then sooner or later the "reward" will be introduced.
