$f:\{1,2,3....\}→\{1,4,9....\}$

$f(x)=x^2$ → codomain = range

for every x there exists atleast one x

→ it is onto

$f(x_1)=f(x_2)⇒x_1=x_2$   (one-one)

The correct answer is option (1) - Bijective