In Spring Boot, the @ExceptionHandler annotation is used to handle exceptions at the controller level. This annotation allows you to define methods within a controller that can handle specific exceptions thrown by that controller. The other options, such as @ControllerAdvice, @RestController, and @RequestMapping, have different roles and are not used for handling exceptions directly at the controller level.

In Spring Boot tests, you can override properties defined in application.properties by using the @TestPropertySource annotation to load custom properties. Option (1) is incorrect as it's not a standard practice. Option (3) is incorrect because modifying application.properties directly in test code is not recommended. Option (4) is incorrect; properties can be overridden.

Spring Boot supports reactive programming in conjunction with traditional MVC patterns by automatically adapting to the reactive or traditional approach based on the project's dependencies. It uses conditional configuration and auto-detection of libraries to determine whether to configure the application as reactive or traditional. This allows developers to seamlessly integrate reactive and non-reactive components within the same application, providing flexibility and compatibility with both programming models.

In Spring Boot, enabling "Lazy Initialization" can help in reducing the startup time of the application. Lazy initialization means that beans are created and initialized only when they are first requested, rather than eagerly during application startup. This can significantly improve startup performance, especially for large applications with many beans, as it avoids unnecessary upfront bean creation.

In Spring Boot, the @Cacheable annotation is used to indicate that a method's return value should be stored in the cache. This annotation is applied to methods that you want to cache, and it allows you to specify caching parameters such as the cache name and the key. It is a fundamental annotation for caching in Spring Boot.

To implement custom authentication logic in Spring Security, developers can create a bean of type AuthenticationProvider. This allows developers to define their own logic for authenticating users, such as checking credentials against a database or external system. The AuthenticationProvider interface is a key component for custom authentication.

The UserDetailsService interface in Spring Security is used to load user-specific data and plays a crucial role in authentication mechanisms. It's responsible for fetching user details from a data source, such as a database, and returning them as a UserDetails object. This interface is a key component in the authentication process, allowing Spring Security to validate user credentials and create an Authentication object.

To secure RESTful web services in Spring Security using OAuth2, you should configure OAuth2 client and resource server details in the Spring Security configuration. Option 1 and Option 4 do not represent the correct way to secure RESTful services with OAuth2. Option 2 suggests configuring OAuth2 properties in the wrong place, and it is not a standard approach.

To support custom permissions in Spring Security, you should implement a custom PermissionEvaluator (Option 2). This interface allows you to define custom logic for evaluating permissions. Creating a custom security interceptor (Option 1) or modifying the Spring Security core library (Option 3) is not recommended and can be complex and error-prone. Predefined permission expressions (Option 4) may not cover all custom requirements.

In Spring Boot, you can access a defined property in the application properties file within a Spring Boot application class by using the @Value annotation. This annotation allows you to inject property values directly into your beans, making it easy to access and use configuration properties within your code. The other options are not standard ways to access properties in Spring Boot.