Final answer:
Option A (Protection, Absorption, Secretion, Sensation) identifies the four essential functions of epithelial tissue: protection, absorption, secretion, and sensation.
Step-by-step explanation:
The essential functions of epithelial tissue include protection, absorption, secretion, and sensation. These tissues are closely packed cells that form the covering or lining of body parts, thereby guarding against physical, chemical, and biological wear and tear. Epithelial tissues also control permeability and the selective transfer of materials, besides having cells connected by tight junctions to form an impermeable barrier. Furthermore, they play a role in the free exchange of molecules via gap junctions and are involved in attachment through anchoring junctions.
Given the functions mentioned, option A (Protection, Absorption, Secretion, Sensation) is the correct answer to the question regarding the four essential functions of epithelial tissue.