The magnitude of a C-H bond dissociation energy (BDE) depends on two main factors:
  • s-character of the C-H bond: the order is $$sp \gt sp^2 \gt sp^3$$. Greater s-character shortens and strengthens the bond, therefore increases its BDE.
  • Stability of the radical produced after homolytic cleavage: the more stabilised the radical, the lower the BDE of the parent bond.

The four bonds listed in Column J are:

P : Benzylic C-H in $$C_6H_5CH_3$$ - cleavage gives a benzylic radical that is resonance-stabilised.

Q : Allylic (or tertiary) C-H - cleavage gives an allylic/tertiary radical that is highly stabilised by resonance or hyperconjugation.

R : Primary aliphatic C-H - cleavage gives a primary alkyl radical, only weakly stabilised.

S : Vinylic (sp$$^2$$) C-H - the C atom is $$sp^2$$ hybridised; the radical obtained is least stabilised, but the high s-character makes the bond very strong.

Arranging them in ascending order of radical stability (and therefore descending order of BDE):
  Radical stability : Allylic/tertiary > Benzylic > Primary > Vinylic
  Corresponding BDE : Vinylic (highest) > Primary > Benzylic > Allylic/tertiary (lowest)

Column K provides four numerical ranges (i to iv) that follow the same strength order:
i : highest (≈ 460 kJ mol$$^{-1}$$)   (S)
ii : next (≈ 410 kJ mol$$^{-1}$$)   (R)
iii : next (≈ 380 kJ mol$$^{-1}$$)   (P)
iv : lowest (≈ 345 kJ mol$$^{-1}$$)   (Q)

Hence the correct matching is
P → iii, Q → iv, R → ii, S → i.

Therefore, the correct option is:
Option A which is: P - iii, Q - iv, R - ii, S - i