If the function f : ℕ → ℕ is defined as \(f(n)=\left\{\begin{array}{ll} n-1, & \text { if } n \text { is even } \\ n+1, & \text { if } n \text { is odd } \end{array}\right.\), then
(A) f is injective
(B) f is into
(C) f is surjective
(D) f is invertible
Choose the correct answer from the options given below :
1
(B) only
2
(A), (B) and (D) only
3
(A) and (C) only
4
(A), (C) and (D) only