Final answer:
The requirement for a CPA firm to designate itself as 'Members of the American Institute of Certified Public Accountants' is that the firm must be a registered member firm of the Institute and be current with all dues payments.
Step-by-step explanation:
In order for a CPA firm to designate itself as "Members of the American Institute of Certified Public Accountants", the correct requirement is:
A. the firm must be a registered member firm of the Institute and be current with all dues payments.
CPA firms are required to be registered members of the Institute and must maintain current dues payments to be designated as members of the AICPA. It is not necessary for all CPA owners within the firm to be members of the Institute.