Final answer:
In the United States, external auditing services are provided by Certified Public Accountants (CPAs), who are qualified professionals that have passed the Uniform CPA Examination and obtained necessary certification and experience. Option a.
Step-by-step explanation:
Persons in the United States who provide external auditing services are designated as Certified Public Accountants (CPAs). A CPA is a professional who has passed the Uniform CPA Examination and has met additional state certification and experience requirements for certification as a CPA.
These professionals are qualified to perform a variety of accounting services, including external auditing, which is the independent examination of financial statements by an auditor to ensure that they present fairly the financial position and results of operations in accordance with generally accepted accounting principles (GAAP).
While the Comptroller of Public Accounts also deals with accounting and financial matters, the comptroller's role is typically associated with a state-level position, and the responsibilities include maintaining the state's accounting records and collecting state taxes and revenues.
The comptroller is not typically involved in the external auditing services provided to companies and organizations.
In contrast, the option of Chartered Accountant is a title used in many countries outside of the United States but is not a designation for auditors within the U.S. Certified Management Accountants (CMAs) and Certified Financial Accountants (CFAs) have different specializations and are not primarily focussed on external auditing.
So Option a.