Which statement is true about interface variables?

• A. They are always private and cannot be accessed outside the interface.
• B. They are implicitly public, static, and final.
• C. They can be modified within the interface.
• D. They must be declared as abstract.

Answer: (B)

Interface variables in Java are inherently defined to be public, static, and final. This means that any variable declared in an interface is automatically accessible from any class that implements that interface, as they are public. Being static signifies that the variable belongs to the interface itself rather than to any instance of a class that implements the interface. The final modifier indicates that once a value is assigned to the variable, it cannot be changed, ensuring that all implementations of the interface have a consistent value for that variable.

This design allows for constants to be defined within an interface, which can then be used throughout classes that implement the interface. Consequently, it helps promote a clear and cohesive design that relies on consistent values shared across different implementations.

The other options do not align with the characteristics of interface variables. For instance, interface variables are not private—this contradicts their purpose. They also cannot be modified, as the final keyword prohibits any subsequent reassignment. Lastly, abstract declarations pertain to methods rather than variables, as interface variables inherently do not support an abstract definition.