The correct option is A Ventricles
The four cavities of the human brain are called as ventricles. The two largest are the lateral ventricles in the cerebrum, the third ventricle is in the diencephalon of the forebrain between the right and left thalamus and the fourth ventricle is located at the back of the pons and upper half of the medulla oblongata of the hindbrain. The ventricles are concerned with the production and circulation of cerebrospinal fluid.