Scientists dye cells using fluorescent molecules that bind to the cell membrane so that the cells can be seen under a microscope. Proper visualization of a human egg cell under the microscope requires that a high enough concentration of dye molecules be attached to the cell membrane. Which value would be important for determining how many dye molecules would need to bind to the egg in order to visualize it?

a. the volume of the egg
b. the surface of the egg
c. both the surface and the volume of the egg