In which gastrointestinal tunic are general receptors located?

The answer is the sub-mucosa layer. This layer is highly inundated with nerve supply that controls the secretions (hormones, mucus, and enzymes) of glands in the mucosa layer. It is the depolarization of these chemoreceptors and pressoreceptors that activate responses such as salivation.  This layer also contains the lymphatic and blood vessels that nourish the GI cells.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.