C. common ancestry.
Common ancestry is identified in the genes. Selection forces are the drives to these physical and composition changes of an organism however, it can be traced back.
Adaptation processes occur to help species survive and thrive in the ecological balance of life. Structural adaptations are physical features of an organism that adapted through time. An example of this are the bills of a bird and the fur of bears that they generally need for their survival; birds for hunting, and bears to protect them from low climate areas.
