You should select your possible reactors and also you should tell the temperature conditions. Should we operate at maximum or minimum temperature conditions? To prove your selection, make some example calculations at least $2$ different temperatures.

A$+$B$->$D $-$r$=1000*$exp$(-6000/$T$)*$CA$^2*$CB $($T in Kelvins$)$

A$+$B$->$U $-$r$=8*$exp$(-2000/$T$)*$CA$^1\mathrm{.}5$