The discovery of pollen in various sedimentary layers has allowed paleontologists to correlate the existence of ancient animals with the vegetation on which they often subsisted. the preservation of pollen in sedimentary layers is an example of a/n

The correct answer is Palynology.  

Palynology refers to the study of particles or dust that are scattered. A palynologist examines particulate samples gathered from water, air, or from deposits including sediments of any age. The identification and condition of those particles, inorganic or organic provide the palynologist with the clue to the environment, life, and energetic conditions that originated them.  

It is the branch that deals with the contemporary and fossil palynomorphs, like spores, pollen, and others, in combination with the kerogen and the particulate organic matter found in the sediments or the sedimentary rocks.  

Pollen are male gametes produces by flowers to undergo fertilization of female gametes or ovules to form fruits and seeds. It is an important product necessary for maintaining the life cycle of plants, by participating in reproduction. Palynology, is a scientific discipline concerned with the study of pollen for the purpose of different scientific applications like archeology, allergy studies and forensic studies. The fossilized pollen is studied for archeological and forensic purpose. When the pollen grains are dispersed from the plants by the action of wind or any other pollinating agent. These grains may fall down in the soil. The strata of different soil layers preserve the pollen after attaining compaction in the form of sedimentary rocks. Hence, pollen grains gets preserved as a fossil in the sedimentary rocks. The study involved in this process is palynology. If the pollen is fossilized along with a organism trace residues. It can determine the existence of a particular organism in a geological time scale.

since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.