Consider two flow reactors. Reactor A is a PFR with a constant volume of $3$ mand a volumetric flow rate of $1,5$ mh$-1.$ Reactor B is a CMFR with a constant volume of $1$ m and a volumetric flow rate of$0\mathrm{.}5$ mih", Water containing species C enters both reactors with an inlet concentration of C$.$ Within each reactor, the species undergoes first$-$order decay with a rate constant k$.$ Which reactor has the longer mean residence time $0?$