What phenomenon is indicated by the alignment of the sun and moon?

The correct answer is spring tides, which occur when the sun and moon align in a way that their gravitational forces combine to exert a stronger pull on the Earth's waters. This alignment takes place during the full moon and new moon phases. During these times, the high tides are higher than usual, and the low tides are lower, creating a more pronounced difference between the two. The phenomenon is a result of the synergy between the moon's gravitational pull and the sun's gravitational influence, intensifying the tidal range.

Normal tides refer to the regular tidal cycles that occur daily and are not specifically related to the alignment of celestial bodies. Neap tides occur when the sun and moon are at right angles relative to the Earth, resulting in less extreme tides. Coastal tides, while relevant to the variation of water levels near shores, do not specifically denote any particular astronomical alignment. Thus, spring tides specifically highlight the importance of the alignment of the sun and moon in influencing tidal movement, making it the correct choice in this context.