Question

A colour blind person cannot distinguish

• A. Red and green
• B. Green and blue
• C. Yellow and white
• D. Black and yellow

Answer 1

The correct option is A Red and green

Colour blindness is of three types, the different anomalous conditions are:

• Protanomaly, which is a reduced sensitivity to red light,

• Deuteranomaly which is a reduced sensitivity to green light and is the most common form of colour blindness
  
• Tritanomaly which is a reduced sensitivity to blue light and is extremely rare.

Hence, a colour blind person cannot distinguish red and green (blue light is extremely rare)

So, the correct answer is 'Red and green'.