What part of the brain connects to the spinal cord and maintains essential functions such as heart rate and breathing?

The brain stem is the correct answer because it serves as a critical structure that connects the brain to the spinal cord and is responsible for regulating many of the body’s vital functions. It plays an essential role in controlling autonomic functions, which include heart rate and breathing. The brain stem comprises three main parts: the midbrain, pons, and medulla oblongata. Among these, the medulla oblongata is particularly important for regulating heart rate and the respiratory rate.

In contrast, the cerebellum primarily focuses on coordination and balance rather than vital autonomic functions. The cerebrum is the largest part of the brain, responsible for higher-order functions such as thought and voluntary movement but does not directly manage the autonomic processes that sustain essential bodily functions. The limbic system is associated with emotions, memory, and arousal but is not involved in the basic physiological processes managed by the brain stem. Thus, the brain stem's connection to the spinal cord and its role in vital regulatory functions highlight why it is the correct choice.