The answer to this question is the sacrum. The sacrum is a triangular bone that forms the base of the spinal column. This bone has a vital role in the skeletal system and also supports the weight of the upper body of a person and this bone and many nerves are inside the sacrum.
        
             
        
        
        
The brain and the spinal cord.
        
             
        
        
        
Answer: b. A compound is a pure substance because its molecule cannot be broken down into simpler particles by physical means.