Which of the following is NOT one of the three main parts of the brain?

The medulla oblongata is indeed an essential part of the brain, but it is not classified as one of the three main parts of the brain. The three main parts are typically identified as the cerebrum, cerebellum, and brainstem. The cerebrum is responsible for higher cognitive functions such as thinking, learning, and decision-making. The cerebellum plays a crucial role in the coordination of movement and balance. The brainstem, which includes structures like the medulla oblongata, midbrain, and pons, manages basic life functions such as breathing and heart rate. While the medulla oblongata is part of the brainstem, the question specifically asked for the three main divisions of the brain, which do not include the medulla oblongata as a standalone category.