Which of the Presented Mechanisms Would Be the Most Energetically

Multiple Choice

Which of the presented mechanisms would be the most energetically favorable and thus the most likely mechanism to actually occur for the following free radical chain reaction?
(bond dissociation energies - H-H = 104 kcal/mol; Cl-Cl = 58 kcal/mol; H-Cl = 103 kcal/mol)
H₂ + Cl₂ 2 HCl

A) H₂ H∙ + H∙
H∙ + Cl₂ → Cl∙ + HCl
H∙ + Cl∙ → HCl

B) Cl₂ Cl∙ + Cl∙
Cl∙ + H₂ → H∙ + HCl
H∙ + Cl₂ → HCl + Cl∙

C) H₂ H∙ + H∙
H∙ + Cl₂ → Cl∙ + HCl
Cl∙ + H₂ → HCl + H∙
D) Cl₂ Cl∙ + Cl∙
Cl∙ + H₂ → H∙ + HCl
H∙ + Cl∙ → HCl