Concept:The diagram shows a cell engulfing a particle, a process called phagocytosis.Explanation:In humans, phagocytosis is mainly carried out by white blood cells such as neutrophils and macrophages.These white blood cells are transported in the blood.Blood is the fluid tissue of the circulatory system.Therefore, the biological system containing cells that perform this process is the circulatory system.Answer:B. circulatory
