Which part of the brain is primarily responsible for higher-level functions such as reasoning and problem-solving?

The cerebral cortex is the correct answer because it is the outermost layer of the brain and is crucial for higher-level cognitive functions. This region is responsible for complex processes such as reasoning, problem-solving, decision-making, and planning. It is organized into different areas, with specific regions associated with various functions. For instance, the prefrontal cortex is particularly involved in executive functions, which include managing cognitive tasks related to logic and problem-solving.

The other parts of the brain play different roles; the cerebellum primarily coordinates motor functions and balance, the medulla is involved in regulating vital autonomic functions such as heart rate and respiration, and the thalamus serves as a relay station for sensory information to the cerebral cortex but does not engage in higher cognitive processes. Thus, the cerebral cortex stands out as the center for reasoning and problem-solving capabilities in the brain.