Maven is the primary build tool used for Spring Boot projects by default when generating a project using start.spring.io. Spring Boot favors Maven as the build tool due to its wide adoption and robust capabilities for managing dependencies and building projects. Other build tools like Gradle can be used but are not the default choice.

In this scenario, you should use mock objects or frameworks like Mockito to simulate the interactions with other components. This allows you to isolate the component being tested and control its behavior during testing without affecting other components.

For advanced scenarios in service discovery, such as region isolation, the Spring Cloud component Ribbon can be configured along with Eureka. Ribbon is a client-side load balancer that works seamlessly with Eureka for client-side load balancing. It allows you to customize load-balancing strategies and apply them to different scenarios, such as region-based routing or weighted load balancing, by configuring properties and policies.

@DataJpaTest is used to test database interactions. It loads a minimal Spring application context that focuses on JPA (Java Persistence API) components such as repositories. This is helpful for testing data access and database-related functionality.

You can implement a fallback mechanism for exceptions not caught by any @ExceptionHandler methods by defining a default exception handler method in a base controller class. This method acts as a catch-all for unhandled exceptions in that specific controller. It's important to note that this approach is controller-specific and may not handle exceptions from other controllers. It provides a way to handle uncaught exceptions within the scope of the controller.

To ensure the correct order of beans in an injected collection, you can use the @Order annotation on each bean and specify an order value. Spring will then inject the beans in ascending order of their order values. This is a common practice to establish the desired order for beans that need to be injected in a specific sequence.

In Spring Boot, the "@Conditional" annotation is used to specify conditions that must be met for a component to be registered. This annotation is often used in combination with other conditional annotations like "@ConditionalOnProperty" to conditionally enable or disable components based on specific criteria.

In Spring Boot, you can create custom auto-configurations by defining a class with the @Configuration annotation and using the @ConditionalOnClass annotation to conditionally enable the configuration based on the presence of specific classes. This allows you to control when your custom auto-configuration should be applied. The other options do not directly relate to creating custom auto-configurations in Spring Boot.

To handle exceptions during form binding in Spring Boot, you can use the setBindingExceptionHandler method of the DataBinder class. This method allows you to set an exception handler specifically for form binding. The other options do not correspond to valid methods for handling exceptions during form binding in Spring Boot.

In Spring Boot, you can exclude specific auto-configuration classes from being applied by using the "spring.autoconfigure.exclude" property in the application properties file. This is helpful when you want to customize your application's configuration and prevent certain auto-configurations from being applied.