Hi, the principle is that knowingly helping is infringement. In the application, we know the copy shop aided, but we have no idea if they did so knowingly. We need to establish that they did so knowingly in order to properly justify the application.
E does exactly this.
C is completely irrelevant to the idea of knowingly aiding. We are looking to have a means to determine if the shop was knowingly aiding. A normative statement about what one should generally do does not do this.
