For (A), f(x)=px+q,(p≠0) is a linear function and the function which are linear are one-one or onto in set of real numbers so, A → II For (B), f:R→R+∪{0} is defined as, f(x)=x2 So, f(−1)=f(1)=1 So, f(x) is not one-one function but range of function is [0,∞) Thus, x2≤0,∀x∈R So, f is onto but not one-one. Therefore, B → IV For (C), f:N→N is defined as, f(x)=n2+2n+3 is one-one but not onto because there is no value of n for which f(n)=3 So, C → III Considering the options the correct option is (1).