Proteins is made up of a sequence of an amion group, a carboxyl group, a hydrogen atom and a side chain bonded to the centralcarbon atom.
Option C would be correct. The organ system can plays many parts at one time. Also, it is the only system listed.
Hope this helps!
Atomic #= 16
Mass=32.06
Neutrons=16 (subtract the atomic number by the mass(32-16=16))
Non metal