A) Biconcave cells
B) Cells can change shape
C) Cytoplasm contains hemoglobin
D) Nucleus is centrally located
E) Main role is transporting blood gases

A) Hemorrhage
B) Vitamin B₁₂ deficiency
C) Iron deficiency anemia
D) Restricted blood flow to the kidney
E) Both "Vitamin B₁₂ deficiency" and "Iron deficiency anemia" are correct.

A) Delivery of O₂ to tissue cells
B) Transport of digestive enzymes to the small intestine
C) Maintenance of DNA content of egg cells
D) Transport of neurotransmitters across synapses
E) Electrical stimulation of the heart