Which part of the human body cannot be transplanted?

The part of the human body that cannot be transplanted is (d) Brain. Unlike other organs like the kidney, heart, and lung, which can be surgically removed from one individual and transplanted into another to replace damaged or diseased tissue, the brain cannot be transplanted.
The brain is the central organ of the nervous system and controls most bodily functions, including consciousness, cognition, and movement. Its intricate structure and highly specialized connections make it impossible to transplant without irreversibly disrupting essential neural pathways and functions.
While researchers continue to explore advances in neurology and neurotechnology, including brain-computer interfaces and neural prosthetics, transplanting an entire brain from one person to another remains beyond the realm of current medical science and ethical considerations. Therefore, unlike other organs that can be transplanted to save lives, the brain is not currently a candidate for transplantation.