Which zone extends to the highest spring tide line?

• A. Dunes
• B. Barrier Flat
• C. High Salt Marsh
• D. Lagoons

Answer: (C)

The main idea is how far tidal flooding reaches inland during the strongest tides. The highest spring tides push the water level farthest up the shore, so the zone that reaches that upper edge is the high salt marsh. This area sits in the upper intertidal zone, where salt-tolerant plants grow and the land is regularly inundated only during the tallest tides. Dunes stay largely above normal tidal influence and are dry most of the time, barrier flats are lower and flood more frequently but don’t extend as far up the shore as the marsh, and lagoons are behind barriers, not part of the seaward edge that experiences the spring tidal line.