The elements which show both positive and negative oxidation states : i) N; ii) H; iii) O and iv) F

The Oxidation states of the for the elements provided in the question are as follows:

(i) N : -3, +3,+5

(ii) H : -1, +1

(iii) O : -2, -1, +1, +2

(iv) F : -1

N, H and O have both positive and negative oxidation states.

Therefore, Option A is the correct answer