Hola a todos!

Estoy tratando de entender un ejercicio pero no me es claro el por qué de la respuesta que está en el libro, el ejercicio es el siguiente:

public class Organic<E> {
void react(E e) {}
public static void main(String[] args) {
Organic<? extends Organic> compound = new Aliphatic<Organic>();
//Organic<? super Aliphatic> compound = new Aliphatic<Organic>();
compound.react(new Organic());
compound.react(new Aliphatic());
compound.react(new Hexane());
}
}

class Aliphatic<F> extends Organic<F> {}
class Hexane<E> extends Aliphatic<E> {}


Las opciones de respuesta son:

Which, taken independently, are true? (Choose all that apply.)
A. If line 5 is uncommented, compilation fails due to an error at line 7.
B. If line 5 is uncommented, compilation fails due to an error at line 8.
C. If line 5 is uncommented, compilation fails due to an error at line 9.
D. If line 6 is uncommented, compilation fails due to an error at line 7.
E. If line 6 is uncommented, compilation fails due to an error at line 8.
F. If line 6 is uncommented, compilation fails due to an error at line 9.

Las respuesta es: A, B, C, and D are correct.

Pero no me queda del todo claro porque al quitar el comentario a:

Organic<? extends Organic> compound = new Aliphatic<Organic>();

Ninguna de las 3 llamadas al método react funciona.

Muchas gracias de antemano!!