Answer:
oxygen
Explanation:
oxygen is an essential nutrient which the body needs especially during respiration.
it help the blood cells do provide energy.
without oxygen, there is no gaseous exchange
Answer:White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multipotent cells in the bone marrow known as hematopoietic stem cells. Leukocytes are found throughout the body, including the blood and lymphatic system.
Explanation: