What are the articles of the National Constitution that are applicable to the administrative procedure?

I. Article 16: Equality of treatment.
II. Article 18: Due process, which includes the right to a process that respects the guarantees of defense in the procedure.
III. Article 19: Legality, which obliges to act with unrestricted adherence to the laws.
a. Only I is correct.
b. Only II is correct.
c. Only III is correct.
d. Both I and II are correct.
e. All of them are correct.