Reactant A converts to product D through the given mechanism (with the net evolution of heat): A → B, slow; Δ H =+ ve; B → C, fast; Δ H =- ve; C → D,…

Reactant A converts to product D through the given mechanism (with the net evolution of heat) : $$\begin{array}{lll} \text { A } \rightarrow \text { B } & \text { slow; } & \Delta \mathrm{H}=+ \text { ve } \\ \text { B } \rightarrow \mathrm{C} & \text { fast } ; & \Delta \mathrm{H}=-\mathrm{ve} \\ \mathrm{C} \rightarrow \mathrm{D} & \text { fast } ; & \Delta \mathrm{H}=-\mathrm{ve} \end{array} $$ Which of the following represents the above reaction mechanism ?