What describes spring tide?

• A. The regular rise and fall of the ocean's surface influenced by the moon's gravity pulling on earth
• B. Water bulges toward Moon
• C. The time at which the tide reaches its lowest level
• D. Sun and Moon are aligned; strongest

Answer: (D)

Spring tides occur when the Sun and Moon line up with the Earth, so their gravitational forces reinforce each other to produce the strongest tides. This alignment happens during new moon and full moon phases, when the Moon is on the same line as the Sun from our point of view. The result is higher high tides and lower low tides, increasing the tidal range. The other ideas describe parts of the phenomenon (one body pulling toward the Moon) or merely the timing of a low tide, but they don’t capture why the tides are at their strongest.