Covers the accounting equation

Correct answer: D. River deposition exceeds marine reworking and distributaries extend seaward

A bird-foot delta develops where a sediment-rich river builds long, narrow distributaries outward into relatively quiet coastal water. River deposition must exceed the ability of waves, tides, and currents to redistribute the sediment laterally. The distributaries then project like toes, producing the characteristic shape. High wave energy or little sediment would destroy this pattern, so option D is correct.

Correct answer: A. When a natural levee breaks and floodwater spreads sand and silt over the floodplain

A crevasse splay forms when a river’s natural levee or bank is breached during flooding. Water escapes rapidly onto the floodplain, loses energy, and deposits a small fan-shaped spread of sand, silt, and other sediment beside the breach. Option A describes this sequence. Sea-arch collapse, cirque erosion, and mushroom-rock formation are coastal, glacial, and aeolian processes, respectively.