The answer is (4) amino acid. This molecule has one carboxyl and one amidogen linked at the same carbon atom. This is the property of amino acid. So this is an amino acid.
Because it is a covalent bond meaning that they share the electrons to achieve full valence.
The SI base units and their physical quantities are the metre for measurement of length, the kilogram for mass, the second for time, the ampere for electric current, the kelvin for temperature, the candela for luminous intensity, and the mole for amount of substance.