Enthuware

I think thet the inheritance makes code more reusable.

As you write the questions ambiguity could be removed by changing the option from

"More efficient code" to "More efficient code at runtime"

This is more likely to appear in the actual test.

I agree. The code can be more efficient in a way that the programmer doesn't have to write duplicate code.
This way it's a very subjective answer.

When a programmer doesn't have to write duplicate code that means the programmer is efficient, not the code. Efficiency of the code is always about execution time of that code.

It protects the code by preventing extension.
Just the reverse is true. Extension is how polymorphism is achieved.
Why, without polimorphism programmer must write too much code for every single case so it do code more extension. And polimorphism preventing extension. Why not?

Ok, I understand the dynamics with which the exact method to be called from the jvm is deduced at runtime. From a research I have seen in IT the adjective "dynamic" is used only in relation to the "dynamic analysis of the code", which means, therefore, "more dynamic code"?
Thanks