Answer
$Aaron$ must be a $knave$, because a $knight$ would never make the false statement that all of them are $knaves$.
If $Bohan$ is a $knight$, then he would be speaking the truth.
If $Crystal$ is a $knight$, so that is one possibility.
On the other hand, $Bohan$ might be a $knave$,
in which case his statement is already false, regardless of$Crystal$'s identity.
In this case, if $Crystal$ were also a $knave$, then $Aaron$ would have told the truth, which is impossible.
So there are two possibilities for the ordered triple ($Aaron$, $Bohan$, $Crystal$),
namely ($knave$, $knight$ , $knight$ ) and ($knave$, $knave$, $knight$ )
Work Step by Step
$Aaron$ must be a $knave$, because a $knight$ would never make the false statement that all of them are $knaves$.
If $Bohan$ is a $knight$, then he would be speaking the truth.
If $Crystal$ is a $knight$, so that is one possibility.
On the other hand, $Bohan$ might be a $knave$,
in which case his statement is already false, regardless of$Crystal$'s identity.
In this case, if $Crystal$ were also a $knave$, then $Aaron$ would have told the truth, which is impossible.
So there are two possibilities for the ordered triple ($Aaron$, $Bohan$, $Crystal$),
namely ($knave$, $knight$ , $knight$ ) and ($knave$, $knave$, $knight$ )
