Object-Oriented Programming

In C#, indexers cannot be static because they are designed to index instance data using this, whereas properties can be declared static. The other options are incorrect because both properties and indexers can participate in inheritance.

Abstract methods declare method signatures without implementation. Non-abstract child classes must provide concrete implementations. Abstract child classes can choose to implement abstract methods or declare them abstract again for their own children to implement.

In C#, structs cannot inherit from other structures or classes, but they can implement interfaces, define constructors (though parameterless constructors have specific restrictions depending on the C# version), and contain members like methods, properties, and events. Since this is an MC-2 (multiple response) question, all three selected options are correct statements.

Generic constraints in C# restrict type parameters. Derivation constraints specify a base class, constructor constraints require a parameterless constructor, and reference/value type constraints constrain to class or struct. Generic constraints CAN be used with structs - they're not limited to classes.

C# does allow static methods to use generic type parameters. The type parameter can be defined at the class level (all methods share it) or at the method level (only that method uses it). Static methods can both access class-level type parameters and define their own method-specific type parameters.

In C#, a delegate defined inside a generic class can reference and use the generic type parameters of that enclosing class, allowing it to work dynamically with different types specified at instantiation.

In .NET, generic types can be marked with the [Serializable] attribute just like non-generic types, enabling them to be serialized for storage or transmission.

Types can define multiple generic parameters. Dictionary is a common example with two type parameters, and you can define your own types with three or more.

Generics work with structs just like classes. Nullable is a perfect example of a generic struct in .NET.

Java bytecode can always be decompiled back to readable source code using tools like JD-GUI or CFR. Code obfuscators make reverse engineering more difficult by renaming variables and obscuring logic, but cannot prevent decompilation entirely.

Java compiles to bytecode, not native ELF binaries. Bytecode can be decompiled back to readable Java code using widely-available tools. Code obfuscators rename variables and scramble control flow to slow down reverse engineering, but they cannot prevent decompilation entirely. The sandbox provides runtime security, not compilation protection.

In Java, the Object class is at the top of the class hierarchy - every class implicitly extends Object (except Object itself, which has no superclass). This provides common methods like equals(), hashCode(), toString(), and getClass() to all objects. String and System are classes that inherit from Object, while Final is a keyword, not a class.

Static methods belong to the class, not instances. Hiding (not overriding) occurs when a subclass declares a static method with the same signature - it's resolved at compile-time based on reference type, not runtime object type.