On a diagram of the human brain, the letter 'A' is placed on the large, wrinkled outer layer covering most of the brain's surface. The letter 'A' most likely indicates which of the following brain structures?

• A. Cerebellum
• B. Cerebral cortex
• C. Medulla oblongata
• D. Thalamus

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the question is asking to identify the brain structure labeled 'A' on a diagram, which is described as the large, wrinkled outer layer covering most of the brain's surface.
2. Step 2: Recall that the brain's outermost layer, characterized by its wrinkled appearance, is known as the cerebral cortex. This layer is responsible for higher brain functions such as thought, perception, and voluntary movement.
3. Step 3: Compare the options given: Cerebellum, Cerebral cortex, Medulla oblongata, and Thalamus. The cerebellum is located under the cerebral cortex and is involved in coordination and balance, but it is not the large outer layer.
4. Step 4: The medulla oblongata is part of the brainstem and controls autonomic functions; it is not on the brain's surface. The thalamus is a deep brain structure involved in sensory relay, also not on the surface.
5. Step 5: Conclude that the letter 'A' most likely indicates the cerebral cortex, as it matches the description of the large, wrinkled outer layer covering most of the brain's surface.