We can rule out A because Cell Organ is nonsense.
We can rule out B because it goes in the wrong direction, so by process of elimination the answer is C.
The simplest form of life is the cell, all living things are made of cells. In multi-cellular organisms, many cells with similar functions form tissues e.g. skin tissue or muscle tissue. Tissues work together to make up organs e.g. stomach tissues form the organ the stomach, skin tissues make up the organ known as the skin. Organs work together to to form organ systems, e.g. the digestive system or circulatory system.