"Reduction" involves the act of making something smaller or less in size, quantity, or degree. On the other hand, "promotion" typically refers to the act of increasing or advancing something, such as promoting a cause or moving to a higher rank or position. In short, reduction involves decreasing, while promotion involves increasing or advancing.

The most appropriate antonym for "rebellion" is "loyalty." Rebellion involves resisting or opposing authority, while loyalty implies faithfulness and allegiance to a person, group, or cause. The other options— "uprising" (an act of resistance or rebellion), "sedition" (incitement to rebellion), and "allotment" (the action of allotting or assigning something)— are either synonyms or closely related to the concept of rebellion.