The correct operator to perform bit clear (AND NOT) in Go is the '&' operator followed by the '^' symbol, forming '&^'. This operator clears bits in the first operand based on the corresponding bits in the second operand.

Polymorphic programming is promoted by Go interfaces, enabling different types to be treated uniformly through shared interfaces. This encourages code reuse, flexibility, and adaptability by allowing functions and methods to accept a wide range of types as arguments without the need for explicit type declarations.

The correct option is Query. The Query method in database/sql package is used to execute a SQL query that returns rows. This method is used when you expect rows to be returned from the query execution.

In Go, methods with pointer receivers can modify the fields of the receiver struct, while methods with value receivers cannot. This is because methods with pointer receivers operate on the actual instance of the struct rather than a copy.

Channels are a preferred choice for inter-goroutine communication in Go due to their safety features and built-in synchronization, simplifying the development process.

The "panic" function in Go is used to cause the program to terminate immediately with a runtime error message. This function is typically called when a critical error occurs that cannot be gracefully handled, leading to an abrupt termination of the program.

Middleware designed for rate limiting intercepts incoming requests, checks the request rate against predefined thresholds, and either allows or denies access accordingly. In this case, tracking the number of requests from each client IP address enables you to enforce rate limits effectively. Utilizing a centralized rate-limiting service introduces additional network overhead and potential single points of failure, complicating the architecture. While cloud service providers offer rate-limiting features, they may not be as flexible or customizable as implementing middleware tailored to your application's specific requirements. Implementing a distributed caching mechanism adds unnecessary complexity and overhead, making it less suitable for this purpose.

The correct option is crypto. The crypto package in Go provides implementations for various cryptographic functions, including hashing and encryption, which are essential for authentication systems.

When working with JSON in Go, it's important to avoid common pitfalls to ensure robust and maintainable code. One such pitfall is ignoring JSON field tags, which are used to specify custom field names, omit fields, or handle field visibility during encoding and decoding. Failure to use JSON tags properly can lead to unexpected behavior or incorrect JSON output. Other common pitfalls include ignoring error handling when encoding or decoding JSON, using map[string]interface{} excessively instead of defining appropriate structs, and not considering struct field visibility, which can affect JSON encoding. By being aware of these pitfalls and following best practices, developers can write cleaner and more reliable JSON code in Go.

Yes, in Go, variables can be declared without being initialized. When a variable is declared without an explicit initialization, it's assigned the zero value of its type. This is one of the key features of Go's memory safety, ensuring variables always have a valid value.