Question

which observation could be made in the fossil record where a mass extinction occurred?
organisms disappear and reappear in the fossil record.
many new organisms appear in the fossil record.
the frequency of an organism decreases in the fossil record.
many organisms disappear from the fossil record

Explanation:

A mass extinction event leads to the disappearance of a large number of species. In the fossil record, this would be observed as many organisms disappearing. Organisms disappearing and reappearing (\(1^{st}\) option) is not characteristic of a mass - extinction. New organisms appearing (\(2^{nd}\) option) is more related to speciation after a mass - extinction rather than during. A decrease in the frequency of an organism (\(3^{rd}\) option) is not as significant as the disappearance of many organisms.

Answer:

Many organisms disappear from the fossil record.