I think only d) is correct
again posting screenshot unnecessarily.
If you do this, we can't find duplicates, hence more redundancy in GO platform and Moreover our time will be wasted unnecessarily. I know to type it takes 10-15 min, but atleast for next time if someone ask the same question i can easily find this search
@Prince Sindhiya 4 would be correct, 1 and 2 cannot but why not 3 ?
f(12(x−1))=2(12(x−1))+1=(x−1)+1=x, therefore surjective.
Now suppose f(x1)=f(x2)
then f(x1)2x1+12x1x1=f(x2)=2x2+1=2x2=x2, therefore injective.
I think this reasoning is applied for Rational numbers too. Therefor answer is (C).