Inheritance and Is-A Relationships

Question

Which of the following code segments demonstrates an 'is-a' relationship established through inheritance?

Accepted Answer

```java
public class Quadrilateral { }
public class Rectangle extends Quadrilateral { }
```

Answer

```java
public class Cat { }
public class Dog { }
```

Answer

```java
public class Engine { }
public class Car {
    Engine engine = new Engine();
}
```

Answer

```java
public class House {
    // House contains a door, not a type of door
    Door door;
}
```