Answer:
C. They are sub-cellular structures
Explanation:
Cells have some specific structures present in them. These structures are specialized to perform specific functions. They are called organelles. Organelles are subcellular as they are always present inside a cell. An organelle may be membrane-bound or lack the membrane. For example, the nucleus is an organelle present only on eukaryotic cells as it has an envelop made up of outer and inner membranes. Ribosomes are the organelle that does not have a membrane and are present in both prokaryotic and eukaryotic cells.
