Anegative change in entropy indicates . the products have a greater number of available energy microstates than the reactants. b. the products have a smaller number of available energy microstates than the reactants

B. the products have a smaller number of available energy microstates than the reactants

Explanation:

Entropy is a thermodynamic quantity defined as a criterion to predict the transformation of thermodynamic systems.

In other words: Entropy is the measure of the disorder (or randomness) of a system and is a function of state. That is, it depends only on the state of the system.  

However, as there is chaos that threatens to destroy a system, there are also self-regulation mechanisms, which allow the level of disorder to drop or remain balanced, so that the existence of the system remains; this is known as negative entropy.

To undersand it better:

In the specific case of a reaction, its variation in entropy is matematically expressed as:

(1)

Where:

is the entropy of the products of the reaction

is the entropy of the reactants of the reaction

Now, remembering entropy is a function of the state of the system, if  have a greater amount of available energy microstates than , the variation in entropy of the system will be negative.