One more for E.Goes with the logic.
I vote for C.
E - stabilizers adversely affect flavour agreed, but just the lack of stabilizers cannot ensure good flavour ,and nowhere does the stem say that stabilizers provided consistency which is inferior to what can be got by low constant temps.(cos E say the "best"....)
C - the stem says that though we don't need Stabilizers at low temps, the cost of having low temps in prohibitive and hence gives an incentive to use stabilizers. Hence , investing in a device which would keep a constant temperature would not prevent them from using a cheap substitue to give ice creams the consistency( reduce electricity costs).Hence it is uneconomical.