If the function $f: N \rightarrow N$ 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:

(B) only (A), (B) and (D) only (A) and (C) only (A), (C) and (D) only

(A), (C) and (D) only

The correct answer is Option (4) →(A), (C) and (D) only