What does the suffix "-cyte" refer to?

The suffix "-cyte" is derived from the Greek word "kytos," which means "cell." This suffix is commonly used in medical terminology to denote different types of cells. For example, erythrocytes are red blood cells, and leukocytes are white blood cells. By understanding that "-cyte" refers to a cell, it becomes clear why this is the correct choice.

The other options refer to different biological structures: tissue is a collection of similar cells working together, blood refers to the fluid that circulates through the body containing cells and plasma, and an organ is a group of tissues that perform a specific function. Therefore, these terms do not accurately describe what the suffix "-cyte" signifies.