What happens if a Java class defines no constructors explicitly?
Option A is correct. If no constructor is written, compiler adds a default public no-arg constructor. If any custom constructor is added, the compiler does not auto-generate the default no-arg constructor.
Which feature in Java allows a class to have multiple methods with the exact same name but different parameter lists?
Option A is correct. Method Overloading occurs within the same class when methods share a name but differ in parameter count, types, or order. It is resolved at compile time.
Which mechanism enables Runtime Polymorphism in Java?
Option C is correct. Runtime polymorphism (Dynamic Method Dispatch) resolves calls to overridden methods at runtime based on the actual object instance stored in the reference variable.
What is the requirement for valid Method Overriding in Java subclasses?
Option A is correct. Overriding requires identical method signature (name and parameter types) and compatible return type (covariant return type). Access level cannot be more restrictive.
Which Java modifier prevents a variable from having its value reassigned after initial assignment?
Option B is correct. A 'final' variable acts as a constant. Once assigned a value (either at declaration or inside constructor for instance fields), it cannot be reassigned.