The correct option is A hypothalamus
The hypothalamus regulates body temperature (thermoregulation), urge for eating and drinking. Tumor in hypothalamus will disrupt its functioning resulting in abnormally low body temperature, loss of appetite and extreme thirst. Hence, the brain scan of the man is liable to show tumour in hypothalamus.
The medulla contains centres which control respiration, cardiovascular reflexes and gastric secretions.
Cerebellum maintains the posture and balance of the body.
Spinal cord controls reflex actions.