it is generally thought to be correct to offer a link to the source so that it doesn't look like you're trying to pass off someone else's work as your own.
As to the first part of your post...
The answer is D. The bacteria would all die if you didn't feed them. If you do feed them there will be no environmental pressure to eat nylon and so the mutation will not be selected for.
Also, there is no such thing as an "ID scientist."