Anew kitchen aid refrigerator has a separate cooling system for the freezer, which lessens the humidity in the refrigeration section and reduces spoilage. the change adds to the refrigerator’s utility.

The change add to the refrigerator's ORDINAL utility.
Utility refers to the satisfaction that a consumer derived from  a product  or service that he had purchased. Ordinal utility ranks two products in term of preference, this is why it is also called two commodity model. Ordinal utility theory assume that a consumer will chose a product which gives him an higher level of satisfaction out of two substitutes goods.

Ithinks it’s a and d

D. centrally planned economy hope this ! : d