why woulD poliCy mAkErs nEED to rEgulAtE All Firms thAt proDuCE DiFFErEntiAtED proDuCts
A．BECAusE suCh proDuCts ArE so Common in thE EConomy.
B．BECAusE thErE is no EAsy wAy For poliCymAkErs to Fix thE proBlEm.
C．BECAusE thEy wAnt to EnForCE mArginAl-Cost priCing.
D．BECAusE monopolistiC CompEtitors ArE mAking zEro proFits.