Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

The brain of the average human weighs approximately 14 kilograms and consists of three main parts-the cerebrum, the cerebellum, and the brain stem. The cerebrum is by far the largest of the three parts, taking up 85% of the brain by weight. The outside layer of the cerebrum, 5 the cerebral cortex, is a grooved and bumpy surface covering the nerve cells beneath. The various sections of the cerebrum are the sensory cortex, which is responsible for receiving and decoding sensory messages from throughout the body; the motor cortex, which sends action instructions to the skeletal muscles; and the association 10 cortex, which receives, monitors, and processes information. It is in the association cortex that the processes that allow humans to think take place.

The cerebellum, located below the cerebrum in the back part of the skull, is the section of the brain that controls balance and posture. The brain stem connects the cerebrum and the 15 spinal cord. It controls various body processes such as breathing and heartbeat.

Question: The passages states that the most massive part of the brain is the _____