The @Modifying annotation is used in a Spring Data JPA repository method when you want to execute a non-selecting query, such as an UPDATE or DELETE operation, on the database. This annotation informs Spring that the method will modify the database, allowing it to manage the transaction appropriately. The other options are not suitable scenarios for using @Modifying.

In Spring Boot, the "@Service" annotation is a specialized form of the "@Component" annotation used to represent the application's business logic. It helps Spring identify the class as a service component, allowing it to be automatically detected and used within the application context. The other options, such as "@Repository," "@Controller," and "@Configuration," serve different purposes and are not specifically intended for application logic in the same way as "@Service."

The /metrics endpoint in Spring Boot Actuator is specifically used for exposing application metrics. This endpoint provides valuable information about your application's performance, such as memory usage, garbage collection statistics, and custom metrics you can define. Monitoring these metrics is crucial for ensuring the health and performance of your Spring Boot application.

In a Spring Boot application, you can map application-specific exceptions to HTTP status codes using the @ResponseStatus annotation in custom exception classes. This allows you to define the specific HTTP status code to return when a particular exception is thrown, providing fine-grained control over error responses. The other options are not standard practices for mapping exceptions to HTTP status codes in Spring Boot.

The correct annotation to secure methods in Spring Security is @Secured. This annotation allows you to specify which roles or authorities are required to access a particular method.

The @DataJpaTest annotation in Spring Boot is used for testing the persistence layer. It slices the application context and loads only the relevant beans related to data JPA, making it efficient for testing data access operations.

In Spring Boot, to manually wire a bean, you would use the "getBean()" method of the ApplicationContext. This method allows you to retrieve a bean from the Spring container by its name or class. The other options, such as "registerBean()," "wireBean()," and "fetchBean()," do not represent the correct method used for manual bean retrieval and wiring in Spring Boot.

In Spring Boot, you can use the @Value annotation to inject the value of a specific property into a field. This annotation allows you to inject property values from your application.properties or application.yml file directly into your Spring components, making it convenient to access configuration properties within your application code.

Option 1 is the most common approach. Mockito is a popular Java mocking framework that allows you to mock external dependencies, isolating the microservice being tested.

In Spring Boot reactive programming, the DeferredResult class is used to represent an asynchronous computation result. It allows a controller to start processing a request and return a DeferredResult immediately, deferring the actual result processing to a later time. This is useful for handling long-running or asynchronous tasks in a non-blocking manner.