"Principal office" means:
a. As to Canadian insurers, the office in Canada from which the general affairs of the insurer are directed or managed.
b. As to other alien insurers authorized to transact insurance in one or more States, the office in the United States from which the general affairs of the insurer in the United States are directed or managed.
c. As to all other insurers, the office from which the general affairs of the insurer are directed or managed.