The correct option is C Cerebellum
The cerebellum is located down to the occipital lobe of the cerebrum. The cerebellum is the vital part of the brain that controls the motor movements of the body. Its functions include coordinated movement, balance, posture, speech, etc. Thus in this case of imbalance in riding a bicycle, or not walking is straight line can be caused by dizziness and improper functioning of the cerebellum. So, the correct answer is option C.