<span>The least used
biomedical intervention for changing behavior is
Psychosurgery. Psychosurgery is also known as the neurosurgery for an
individual or people who have a mental disorder. Psychosurgery was used
during the times of 1930's to treat the mental disorder.</span>
I'd have to say d. the hand, because every human (for the most part, no offence intended to anyone) has a hand and is able to make good (or bad, rather) use of it. It's what a person always has access to at any given time or place, even if they don't have access to one of the other options.
Answer:
c. crust, mantle, outer core, inner core
