Final answer:
The principal officer of each executive department has primary responsibility for a written disclosure.
Step-by-step explanation:
In the context of the question, the primary responsibility for a written disclosure lies with the principal officer of each executive department. This is evident from the excerpt provided, which states that the president may require the opinion, in writing, of the principal officer in each executive department on any subject relating to the duties of their respective offices.
Therefore, it is the principal officers who have the primary responsibility for providing written disclosures.