You're building an application where certain operations should only be performed when specific observable properties change. How would you set up a reaction that specifically listens to these properties in MobX?

To set up a reaction that specifically listens to certain observable properties in MobX, you would use the reaction() function. The reaction() function allows you to define custom reactions that depend on specific observables. When the specified observables change, the reaction is triggered, allowing you to perform the desired operations. This approach is suitable when you need fine-grained control over reactions.