Which brain structure is responsible for the human ability to engage in higher mental activity such as thinking and philosophizing

A)  limbic system 
B)  corpus callosum 
C)  cerebellum 
D)  cerebrum

Cerebrum

The largest part of the brain responsible for higher brain functions, including thought, action, emotion, and reasoning.

Higher Mental Activity

Complex cognitive processes such as thinking, reasoning, problem-solving, and planning, which distinguish higher animals and humans.

Limbic System

A sophisticated arrangement of nerve systems and connections in the brain, situated around the cortex's perimeter, responsible for basic instincts and emotional states. This system regulates core feelings including pleasure, fear, and rage, as well as basic urges related to eating, sexual activities, asserting dominance, and nurturing offspring.