Who was at the top of the feudal system hierarchya-serfs b-knightsc-bishopsd-kings e-nobles

D- Kings.

Explanation:

Feudalism is a term that describes the social conditions that were present in Europe between the 9th and the 15th centuries. It is also the term given to the structure of power that defined the politics of the time. Under this system, the people who were at the top of the feudal hierarchy were the kings, who had absolute power in legislation and justice.

radioactive dating, also known as  radioisotope dating  is a process that in  estimating the approximate  age  of  rocks. these data can be analyzed from  the studies dealing with the  decay of the radioactive elements that are present in these rocks. in nature, there are a few types of materials or atoms which are quite unstable and they spontaneously decay or breakdown to form other kinds of atoms.