Red blood cells carry oxygen around the body. In adult they are created in ………… .

Options

A. liver
B. kidneys
C. heart
D. bone marrow

Answer

D

Explanation

In a normal adult, the red blood cells of about half a litre (almost one pint) of blood arc produced by the bone marrow every week. Almost 1% of the body.s red blood cells are generated every day. The balance between red blood cell production and the removal of aging red blood cells from the circulation is precisely maintained.