Which part of the brain is associated with higher-order cognitive functions such as planning and judgment?

The cerebrum is the correct choice because it is the largest part of the brain and is responsible for higher-order cognitive functions. This includes processes such as planning, decision-making, problem-solving, reasoning, and judgment. The cerebrum is divided into two hemispheres, each containing lobes that specialize in different functions. The frontal lobe, in particular, is critically involved in executive functions, which encompass the ability to plan, make decisions, and regulate behavior.

In contrast, the cerebellum primarily coordinates voluntary movements and maintains posture and balance, rather than engaging in higher-order cognitive tasks. The thalamus acts as a relay station for sensory and motor signals to the cerebral cortex but does not engage directly in higher-level cognitive processes. Lastly, the brainstem controls basic life functions such as breathing, heart rate, and sleep-wake cycles, serving more foundational roles rather than complex cognitive activities. Thus, the cerebrum stands out as the central hub for the higher-order cognitive functions mentioned in the question.