The more I study science, the more I am convinced of the WTBTS's lack of even the most basic intellectual integrity and colossal lack of science literacy.
What qualifies a theory as a scientific theory? According to the Encyclopedia of Scientific Principles, Laws, and Theories, a scientific theory, such as Albert Einstein’s theory of gravity, must
Be observable
Be reproducible by controlled experiments
Make accurate predictions
Is evolution a Scientific Theory? Yes. Further, I would be willing to bet that even their own source above (the Encyclopedia of Scientific Principles, Laws, and Theories) would cover it as such.
There is a very good article from Scientific American that can help answer the above points - http://www.scientificamerican.com/article/15-answers-to-creationist/
The WTBTS have done so much eisegesis on the Bible over the years that they seem to feel free to cut/paste other sources as well to suit their needs. Shameless.