What Is the Advantage of the Biconcave Shape of the Red

What is the advantage of the biconcave shape of the red blood cell?

A) The shape makes the cell more resistant to stress.
B) The shape enables a more rapid flow of gases into and out of the cell.
C) The shape occurs because the red blood cell has no nucleus.
D) The shape serves as a means to control the amount of water entering the cell.
E) The shape is unique in that all other cells are more rounded.