Answer:
C. Thrombocytes
Step-by-step explanation:
Blood is a tissue composed of many cells, which include; red blood cells (erythrocytes), white blood cell (leukocytes), platelets (thrombocytes) etc. Of these three types of cells, thrombocytes also known as Platelets are small fragments of a cell with a disk-shape whose primary function is in blood clotting.
In contrast to erythrocytes, and leukocytes (monocytes, lymphocytes) as mentioned in the question, thrombocytes or platelets are not actual whole cells but rather small portion of a cell.