The amounts of financial protection required under this part may be furnished and maintained in the form of:
An effective policy of liability insurance from private sources; or
Adequate resources to provide the financial protection required by §§ 140.11, 140.12; 140.13 or § 140.13a; or
Such other type of financial protection as the Commission may approve; or
Any combination of the foregoing.
In any case where the Commission has approved proof of financial protection filed by a licensee the licensee shall not substitute one type of financial protection for another type without first obtaining the written approval of the Commission.