Fotos rechazadas por problemas de calidad

1. Poor focus, too dark, too much yellow.

2 & 3. Nice kitties.  But Adobe Stock inventory contains millions & millions of perfect cat photographs already. 

https://stock.adobe.com/search?k=cat

For the trunk of trees problem of focusing and under ex and also certainly of white balance. Run your images in PS for the histogram and enlarge your images to 200%.
For the white cat no visible details in the neck and fuzzy ears. For the last cat exposure not uniform between the bottom, the face and the ears. Stock looks for photos that are perfectly exposed and sharp. Put yourself in the buyer's shoes. He does not buy this kind of image to put in an album, but to use it for commercial purposes, such as advertising, illustration, etc... It is very important to provide images that are almost technically perfect. Good luck.