Answer:
D. cannot be upward sloping because this violates the assumption that more is better than less, indicating that one of the goods is a "bad."
Step-by-step explanation:
The curve of indifference is the curve at which the mixture of two goods is represented that the consumer achieves identical satisfaction making the consumer unique.
This can't be sloping upwards, as it makes the contrast between the good and the bad item that describes the good item stronger than the bad item that depicts one of the bad items.