Consider the reaction

$A+B_{\text{R}\text{e}\text{a}\text{c}\text{t}\text{e}\text{r}\text{i}\text{t}\text{s}}{C}_{\text{P}\text{r}\text{o}\text{d}\text{u}\text{c}\text{t}\text{s}}+D$

The potential energy diagram for this endothermic reaction is:

The arrow shown on the above graph represents

a$)Ea(fwd)$

b$)E$

c$)H$

d$)Ea(rev)$