If the second and third ones wear 2G, then the first one must be B. but the first person says NO, so the second and the third could be 1B1G/1G1B/2B.
Next, for the second one, if he saw the third one with G hat, then the second one must be B. But the second one says NO, so the third one must be B.
The answer is option (D): The third one wears a Blue hat.
Credit:
Each person can see others hats,
When person 1 and 2 can’t guess the color of hat ,
it means they see two blue or green and blue so the third hat on blind’s head could be blue 33% or green 66%
(B/B/G or B) (G/B/ G or B)
I think this question is wrong 
@amin_raei98
Hey Amin!
There is nothing wrong with it.
We have 3 blue and 2 green hats.
Each person can see the two other’s hats except the blind one.
When each of these individuals see a blue hat wearing by the two others they can’t guess their own hat’s colour.
Your sentences are true
imagine 2 situation
First:
- Blue 2.green 3.blue
Second:
1.blue 2. Blue 3. Green
In both 1 and 2 say no so I think the answer isn’t D or B
If I tell wrong correct my sentences
@AriHoresh
In both situation that I told you imagine person 1 and 2 say no (can’t guess the color of hat)