In the dynamic equilibrium stage of a chemical reaction, the concentrations of the reactants and products remain constant over time. This occurs when the rate of the forward reaction is equal to the rate of the reverse reaction. At this stage, the system is said to be in a state of balance or equilibrium.

The correct answer to the question is option 'B' - no change in the concentrations of either of the reactants or products. This means that the concentrations of the reactants and products remain constant and do not change during the dynamic equilibrium stage. Let's understand why this is the correct answer.

Explanation:
1. Dynamic equilibrium:
- Dynamic equilibrium is a state in which the rate of the forward reaction and the rate of the reverse reaction are equal, resulting in a constant concentration of reactants and products.
- Both the forward and reverse reactions continue to occur at the same rate, but there is no net change in the concentrations of the reactants and products.
- This stage is represented by a double arrow (⇌) in a chemical equation, indicating that the reaction is reversible.

2. Concentrations of reactants and products:
- In the dynamic equilibrium stage, the concentrations of the reactants and products reach a constant value and do not change over time.
- This does not mean that the concentrations are equal, but rather that they remain constant.
- The reactants continue to react and convert into products, while the products continue to react and convert back into reactants at the same rate.

3. No change in concentrations:
- The equilibrium stage is characterized by a balance between the forward and reverse reactions.
- If there were changes in the concentrations of the reactants or products, it would imply that one reaction is occurring at a faster rate than the other, leading to a shift in the equilibrium.
- Therefore, in the dynamic equilibrium stage, no change in the concentrations of either the reactants or products occurs.

To summarize, in the dynamic equilibrium stage, the concentrations of the reactants and products do not change. This is because the rates of the forward and reverse reactions are equal, resulting in a state of balance. Option 'B' - no change in the concentrations of either of the reactants or products - is the correct answer.