Answer: C. Relative dating
Index fossil refers to the fossils that is used to determine the geological time period which determine the life span of the organism by correlating the strata where the fossil is found. Relative dating is the age determination method of previously existing organisms. It determines the estimated age of an organisms or rock by comparing it with the surrounding layers of sediments or strata.
A relative dating can find the estimated age of the object by using rock layers and index fossils.
