human
Question: Why might a researcher use a variable ratio of reinforcement rather than a fixed ratio?
A: Fixed ratio schedules of reinforcements are more time intensive.
B: Variable ratio schedules of reinforcements produce results more quickly.
C: Variable ratio schedules of reinforcements avoid problems such as generalization and the Premack principle.
D: Variable ratio schedules of reinforcement are more resistant to extinction than fixed schedules.
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option.
gpt
--- Reasoning ---
1. Is the question multiple-choice question?
Yes

--- Answer ---
grounded