Answer: A.
Nucleated red blood cell is less mature than a mature erythrocyte. They
are erythroid precursors that have apoptotic nucleus, the last nucleated stage of
red blood cell production to contain a defined, intact nucleus before the
erythrocyte losses its nucleus.
Moreover, they are confined to the bone marrow, in the peripheral blood in newborns and in uncompensated hemolytic anemia.
