Have ReSharper keep 'using System;' when optimizing usings

Question

I was wondering if there is some option to keep ReSharper from removing just the using System; directive? Perhaps this is configurable somewhere?

Also, is t

Answer 1

Yes, there is such an option: ReSharper->Languages->C#->Namespace Imports. You can add namespaces,that should not be removed, as well as namespaces, that should always be imported.