What is the purpose of the `shared_ptr` aliasing constructor `shared_ptr (const shared_ptr & owner, T* ptr)`?

It creates a second, independent control block for the same object, giving two unrelated owner counts.

It casts the stored pointer to an unrelated type and transfers ownership of that pointer to the new instance.

It deletes the original owner's control block and then adopts its raw pointer under a fresh control block.

It shares ownership of owner's object (keeping it alive) while pointing at a different sub-object `ptr`.

Multiple ChoiceHard 45s

shared_ptr aliasing constructor

What is the purpose of the `shared_ptr` aliasing constructor `shared_ptr<T>(const shared_ptr<U>& owner, T* ptr)`?

Options

1It creates a second, independent control block for the same object, giving two unrelated owner counts.
2It casts the stored pointer to an unrelated type and transfers ownership of that pointer to the new instance.
3It deletes the original owner's control block and then adopts its raw pointer under a fresh control block.
4It shares ownership of owner's object (keeping it alive) while pointing at a different sub-object `ptr`.

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