All of the theories presented so far can be separated into two distinct camps: supernatural (dualist-like) and non-supernatural (physicalist-like). Neither one truly has evidence for their claims, as consciousness is nearly impossible to prove it even exists, let alone how it happens. The famous line cogito ergo sum, meaning "I think, therefore I am" even has flaws. However, assuming that we know we exist, and that we know logic works, it may indeed be possible to prove a theory, although nobody has yet done that. Therefore there is no correct answer, and it is up to the thinker to choose their side.
The question of what things are conscious and what aren't also plays a very large role in choosing a side. The AI experiments with C. Elegans certainly provide support for the physicalist perspective, assuming of course that one believes non-human animals are capable of consciousness. Here is a straw poll for readers to vote on which items they believe are or could be conscious:
None of these sources, however, how consciousness could come about from a physicalist perspective. Luckily, Tarlacı provides an explanation. He says that consciousness is completely physical, and that consciousness is a property of the brain in a similar way to horsepower being a property of engines. The author describes consciousness as our ability to have experiences that we are aware of. He defends functionalism and physicalism, and actually rebuts points made by dualists. Some of his main points against dualism are that it violates the principle of cause and effect, that it doesn’t really explain anything but is a op out, and that it is impossible to actually observe and therefore prove this other part of the conscious mind. Additionally, recent research into the brain shows that the mind and brain, quite obviously, are connected incredibly closely, and that our conscious experiences can be altered by affecting the brain physically.
While Tarlacı provides some interesting ideas, he fails to connect them to the larger whole and doesn't provide an answer to the question "What is consciousness?" However, he does a very apt job of pointing in the right direction, and explaining the property of consciousness in a physicalist way.
My personal opinion
I have always been a physicalist, and I continue to be one after this project. I strongly agree with Tarlacı's theories about consciousness, and I believe that consciousness is a property of matter. For example, arranging matter into the shape of a car engine changes the function of the matter. Before, the pieces were just metals and other unmoving objects. After being assembled, the objects can cause motion in a car, and that can be measured. The metal now has a function as part of a car, just as our brains have functions as being part of consciousness.
One interesting part of this theory is the following. Suppose that someone were to build a supercomputer so powerful it could completely simulate a human brain. Then they used it to run a program that just continually outputted "Hello." Of course, the computer is not conscious at that instant. If, however, one were to run a program that simulated a human brain, the computer would change from an inanimate object to a conscious one, without the matter really changing. Perhaps, then, consciousness is more like the measurement of speed than horsepower.
Citation
Tarlacı, Sultan. "What Should A Consciousness Mind-Brain Theory Be Like?." Neuroquantology 11.2 (2013): 360-377. Academic Search Complete. Web. 4 Dec. 2015.