Does the spinal cord serve as center for sub-conscious thought or reflex action habits synapses?

The correct answer is "reflex action".

The spinal cord is a long, thin, tubular bundle of nervous tissue that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It serves as a conduit for signals traveling between the brain and the rest of the body and also controls many subconscious, or reflex, actions, such as the knee-jerk response.