Concept: This question tests your knowledge of the embryonic origin of different organ systems in humans, specifically focusing on the brain.

Why (A) is correct: The human brain, along with the entire nervous system (including the spinal cord, nerves, and sensory organs), develops from the ectoderm. The ectoderm is the outermost of the three primary germ layers formed during early embryonic development.

Why other options are wrong:

• (B) Mesodermal structures include muscles, bones, connective tissues, circulatory system, and excretory system.
• (C) Endodermal structures include the lining of the digestive and respiratory tracts, and associated glands like the liver and pancreas.
• (D) Meso-endodermal is not a standard germ layer combination for organ origin.

NEET Tip / Mnemonic: Remember "Ecto-Nerve" for Ectoderm giving rise to the Nervous system, and also skin and hair. "Meso-Muscle/Bone/Blood" for Mesoderm. "Endo-Gut/Glands" for Endoderm.

Correct Answer: (A)