"a pattern of evolution in which most change in appearance takes place during a relatively short period of time fits the model of speciation."

An evolution pattern where most appearance changes occur over a short time period matches punctuated equilibrium model.

Explanation:

An evolution pattern where most appearance changes occur over a short time period matches punctuated equilibrium model.

Punctuated equilibrium is an evolutionary biology hypothesis that implies that once an organism occurs in the geological record, the population become constant, exhibiting little evolutionary change for most of geological history.

i would say the prokaryotic cells the prokaryotic cells are less complex, are usually found only in unicellular organisms and have more limited capabilities than eukaryotic cells.

i believe the answer would be b. hope it : )