Concept:Erythrocytes are a class of blood cells best known by their common name.
Explanation:In humans, erythrocytes are biconcave discs that lack a nucleus.
They contain the pigment haemoglobin, which gives blood its red colour.
This pigment also transports oxygen to tissues and removes carbon dioxide.
Since they are the blood cells responsible for these functions, they are called red blood cells.
They are not white blood cells, phagocytes, or leucocytes.
Answer:B. red blood cells.