When millions of rods in our eyes are at work in darkness we call see

A．some may see everything in shades of green
B．few can tell tile difference between blue and green
C．few may think that red, orange and yellow are all shades of green
D．very few may think that everything in the world is in green

A．description of the symptoms of depression
B．brief introduction of depression
C．summary of tile causes of depression
D．list of treatment of depression