Make connections which chemical group is most likely to be responsible for an organic molecule behaving as a base (see concept 3.3)?
a. hydroxyl
b. carbonyl
c. amino
d. phosphate

The correct answer will be option-C.

Explanation:

The functional groups are the group of atoms which gets attached to the skeleton of carbon in a molecule and provides certain characteristics to the molecule.  The main functional group includes hydroxyl, carboxyl, amino, phosphate, methyl carbonyl and sulfhydryl.

These groups could be acidic or basic depending upon them if their structure will be able to take H⁺ ions from solution or donate H⁺ ions.  In the given question, the basic group among these is an amino group which has the ability to accept  H⁺ ions from the solution and form NH₃⁺ ions.

Thus, Option-C is the correct answer.