The following reaction is a mutli$-$step process:

Overal Reaction: $AC$

$H=12\mathrm{.}3k\frac{J}{m}ol$

Step $1$: A $$ B

$k=1\mathrm{.}35**{10}^5\frac{1}{s}$

$H=-2\mathrm{.}5k\frac{J}{m}ol$

Step $2$: B $$ C

$k=2\mathrm{.}73**{10}^5\frac{1}{M}s$

$H=14\mathrm{.}8k\frac{J}{m}ol$

a$.$ What is the rate determining step? $(4$pts$)$