Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Spring tides occur during the new moon and full moon. The Sun and Moon are in a straight line either on the same side of Earth or on opposite sides. Their gravitational pull combines to cause very high and very low tides. Spring tides have the greatest tidal range. Answer: spring
Output:
What tides occur during the new moon and full moon?