Rust can deteriorate a steel pipe to such an extent that it will snap easily, as though it was a twig.
will snap easily, as though it was a twig
will snap easily, like a twig does
will snap easily, as though it is a twig
might snap easily, as though it was a twig
will snap easily, as though it were a twig

[spoiler]We need to use subjuctive mood because the sentence describes a hypothetical event. Ex. If I were rich, I would..... Here were & would are important signals to use subjuctive. But in E (OA), would is not used. Is it correct?[/spoiler]