Final answer:
Selective leaching with an oxidant is a Redox reaction, involving electron transfer between potassium permanganate and the metal hydroxide. The correct answer is option b.
Step-by-step explanation:
The process of selectively leaching a mixed nickel-cobalt hydroxide precipitate in sulfuric acid solution with potassium permanganate as an oxidant is an example of a Redox reaction. This type of reaction involves a transfer of electrons between substances.
In this case, the oxidant (potassium permanganate) is reduced, while the metal hydroxide is oxidized during leaching. Other types of reactions mentioned in the question include acid-base reactions, where a proton (H+) is transferred between substances, and precipitation reactions, which result in the formation of an insoluble solid, as well as complexation reactions that occur when ions form coordinated compounds with ligands.