What is a Marker Interface in Java?
Option E is correct (None of the above). The true answer is 'An interface with no fields or methods used to signal meta-intent to the JVM (e.g., Serializable)'. Marker interfaces (e.g., Serializable, Cloneable) contain zero methods; they tag classes to grant runtime permission or behavior.
What is the result of evaluating 'Java' == new String('Java') in Java?
Option C is correct. The '==' operator checks reference identity. 'Java' resides in String Constant Pool while new String('Java') allocates a distinct object on Heap memory.
In Java 8, what is a Functional Interface?
Option C is correct. Functional Interfaces (annotated with @FunctionalInterface) have a single abstract method (SAM) and serve as targets for $\lambda expressions$.
Which method of the java.lang.Thread class starts thread execution by invoking its run() method on a separate call stack?
Option B is correct. Calling thread.start() registers the thread with the OS scheduler and creates a new call stack before executing run(). Calling run() directly runs on the main stack.
Which package is automatically imported into every Java source file without requiring an explicit import statement?
Option A is correct. java.lang contains core classes (Object, System, String, Math, Thread) and is implicitly imported by the compiler.