Mr C's Visual Acuity Is 20/50

Mr. C's visual acuity is 20/50. This means that he

A) can see 50% of what the average person sees at 20 feet.
B) has perfect vision when tested at 50 feet.
C) can see 20% of the letters on the chart's 20/50 line.
D) can read letters while standing 20 feet from the chart that the average person could read at 50 feet.
E) is legally blind.