What is meant by ‘disproportionation’ of an oxidation state? Give an example

Question

$\begin{array}{1 1} \text{(a) Polymers are carbohydrates that cannot be further broken down into simpler units of other carbohydrates.} \\ \text{(b)When a particular oxidation state becomes equally stable relative to other oxidation states, it is said to undergo disproportionation.} \\ \text{(c) When a particular oxidation state becomes more stable relative to other oxidation states, it is said to undergo disproportionation.} \\ \text{(d) When a particular oxidation state becomes less stable relative to other oxidation states, one lower, one higher, it is said to undergo disproportionation.}\end{array}$