Let f : R → R be defined as f(x) = 3x Choose the correct answer:

(A) f is one-one onto

(B) f is many-one onto

( C) f is one-one but not onto

(D) f is neither one-one nor onto

(A) f is one-one onto

(B) f is many-one onto

( C) f is one-one but not onto

(D) f is neither one-one nor onto