Answer:
Levels of organization
Explanation:
Levels of the organization or hierarchy may be defined as the arrangement of the living things from the simple organisation to the complex organisation. The organisation of living things are atoms, molecules, cells, tissue, organ and organ system.
The given question represent the level of organisation. Here, the simple organisation is molecule. After molecule the mucous cells shows the cellular organisation. Simple columnar epithelia represent tissue organisation. Stomach is the organ and digestive system represent the organ system.
Thus, the correct answer is option (d).
