The correct answer is cerebellum.
The cerebellum is the part of the brain, which is involved in maintaining posture, balance, equilibrium and movement of the skeletal muscles. it is present in the back of the brain, and makes up a significant part of the brain stem.
The Alcohol has a greater impact on this part of the brain, and this structure is very sensitive to alcohol. This is the reason, why the intake of alcohol leads to changes in the walking pattern and balancing the body.