Since all sources must be shown including usage terms and/or license information it is understood that sites such as wallpaper sites, blogs, catalog sites, image hosting sites etc. are not acceptable because they do not show the required information or they display copyright info regarding their content.

Author, you're absolutely right, the rule about wallpapers seems to have disappeared from the guidelines. Still, we have to use sources from sites that offer images under creative commons, which wallpaper sites do not. You still have time to find a useable image and resubmit. If you do, work on the lighting & shadows.

Source 3 is a wallpaper.
Wallpapers are not useable sources. They are mostly copyrighted images, and not offered under Creative Commons licensing.
Please read http://www.pxleyes.com/guidelines/photoshop/
http://www.pxleyes.com/blog/2009/06/how-and-where-to-find-legal-source-images/