Which observation disconfirms the theory that the hunger drive?

The correct answer is option D, that is, individuals whose stomachs have been removed still encounter hunger.  

Generally, the aim of gastrectomy is to work towards settling into a new usual life, by permitting the body to amend and heal after the loss of stomach with time.  

At the similar time, it is essential to try to acquire as much as calorie to reduce rapid weight loss in the initial few months after the surgery, and to consume enough nutrients, which the body requires to help in the process of healing. Initiating to drink and eat can be tough, as it requires determination.  

The familiar perceptions of hunger may be lost, substituted with the feelings of emptiness and weakness. Though at the start drinking and eating is out of inevitability, but soon it becomes a habit, and finally the desire to enjoy and eat of food returns.  

This suggests that the desire to feel hungry is in the brain and is not based on an individual's elucidation of stomach contractions, as the patients who were not able to interpret any signals from a nonexistent stomach do experience hunger.