Code $1$:

if $($number $\%2==0)$

even $=$ true;

else

even $=$ false;

Code $2$:

even $=($number $\%2==0)?$ true: false;

Code $3$:

even $=$ number $\%2==0$;

All three are correct, but Code $1$ is the most concise and the best.

All three are correct, but Code $3$ is the most concise and the best.

All three are correct, but Code $2$ is the most concise and the best.

Code $2$ has a compile error, because you cannot have true and false literals in the conditional expression.

Code $3$ has a compile error, because you attempt to assign number to even.