They only live in warm water temperatures. Also, corals can't live in muddy waters, so the sea must be free of clastic sediment input in order for corals to thrive. Go to next question A6 . The best answer is B. Shelf sediments may be clastic or chemical, but this question asks about clastic sediments. Shelf sediments are fine-grained, mainly mud.
Sediments are coarser in shallower water, e.g. on a beach.
In big storms, some coarser material like sand may be transported from the beach into deeper water, but this is rare. Ripples and hummocky cross-stratification can form due to wave action during storms, so we might see these structures in the few sandstone layers. Go to next question A7 . The only statement that is NOT true here is A, information about the type of organisms that lived in the sand. Body fossils or trace fossils, not cross bedding, provide this information.