Kathy Is a Dichromat

Multiple Choice

Kathy is a dichromat. What do we know for sure about her colour vision?

A) She can only see black and white.
B) She can see black and white plus some colour.
C) Her ability to see black and white is missing.
D) She can detect both red-green and blue-yellow combinations.
E) She has no cones at all in her retina.