According to the periodic trends, atomic radius decreases across a period from left to right due to the increase in effective nuclear charge. The elements given belong to the second period. The correct order of their atomic radii as per NCERT Table 3.6(a) is:

1. Boron (B): Group 13 → 88 \pm (Matches i)
2. Carbon (C): Group 14 → 77 \pm (Matches iv)
3. Nitrogen (N): Group 15 → 74 \pm (Matches ii)
4. Oxygen (O): Group 16 → 66 \pm (Matches iii)

Therefore, the correct matching is: (a) Oxygen → (iii) 66 (b) Carbon → (iv) 77 (c) Boron → (i) 88 (d) Nitrogen → (ii) 74

This corresponds to option (4).