For the liquid phase parallel reactions:

$AR,r_R=K1CA1$;$E1=80K\frac{J}{m}$ole

$AS,r_s=K2CA2$;$E2=120K\frac{J}{m}$ole

The desired product is $R.$ A higher selectivity of $R$ will be achieved, if the reaction is conducted at

a$)$ High temperature in a CSTR

b$)$ Low temperature in a PFR

c$)$ High temperature in a CSTR

d$)$ None of the above