C# OOP: Final Recap & Mega Quiz

You finished all OOP pillars + advanced topics. This 15-question test covers everything. Score 12/15 and you're interview-ready for OOP.

Passing: 12/15 | Time: No limit | Retake allowed

Encapsulation	Hide data. `private` fields + `public` properties with validation. Protects from `Speed = -999`
Inheritance	IS-A relationship. `SportsCar : Car` reuses code. Child gets parent fields/methods. `base` calls parent
Polymorphism	One interface, many forms. `virtual` in parent, `override` in child. `Car c = new SportsCar(); c.Start();` calls SportsCar version
Abstraction	Hide complexity. `abstract class` can't instantiate. `abstract void Start();` forces child to implement

Interface	CAN-DO contract. `interface IDrivable`. No code, no fields. Multiple interfaces allowed. Names start with `I`
sealed	Stops inheritance. `sealed class String` = no child. `sealed override` = no further override
static	No objects. `static class Math` utility only. `static` constructor runs once
new vs override	`new` = method hiding, uses variable type. `override` = true polymorphism, uses object type. Always use override