Which scenario describes a spilling wave?

• A. When wave energy encounters a sloping ocean floor, the crest of white water spreads down the face.
• B. When the wave encounters a sudden decrease in depth such as a reef or steep rise in the ocean floor.
• C. When waves are created on very steep beaches, the wave builds quickly and expends its energy on the beach.
• D. When a wave travels long distances without breaking.

Answer: (A)

Spilling breakers happen when a wave moves over a gently sloping bottom. As depth decreases gradually, the wave slows and grows taller, and the crest becomes unstable, spilling down the front as white water. The scenario describing energy meeting a sloping ocean floor fits this pattern—the crest spreads down the face rather than curling violently or slamming onto the beach. In contrast, a sudden depth change like a reef or steep rise tends to produce a more abrupt break (often a plunging breaker), very steep beaches break with energy mostly on the shore, and waves that don’t break aren’t spilling. So the described behavior matches the spreading, gradual spill of a spilling breaker.