What do the sediments of the abyssal plains mostly consist of A.sand and gravel B.oozes C.seashells D.mud?

Answer 1

This is obviously someone's homework question, so I won't answer directly but will give some clues.

Most shellfish are associated with littoral and near-littoral enviroments.

Large sediment grain sizes require some means to transport them for any significant distance.

The bottom of the ocean may be subject to gentle currents but there is no turbulence, with consequent effects on sediment transport and deposition.

There is no weathering and erosion of deeply submarine features. Turbidity slides - slumping of deposits from terrestrial erosion - from the Continental Shelf do not travel far down or beyond the Continental Slope.

Much of the material descending through the water far from land is fish droppings and dead organisms, and these drift gently down and land very softly. (Oceanographers call it "snow" from its appearance in the water as shown by deep-sea cameras.) Consequently there is little or no compaction by impact. All dead animals landing on the abyssal plain disappear completely in time - even the bones dissolve - although organic compounds may diffuse through the surrounding ground.

Deposition is very slow, as shown by the material accumulated on wrecks in the decades since the ships sank. So compaction by mass is limited and will occur only at depth within a thick deposit.

There may be some very fine wind-borne loess in places but generally the stronger winds are the on-shore, or "sea", ones.

Of the terms you list, one is that used to describe the deposit.

Now work it out from that.