(a) The directors of a domestic mutual insurer may from time to time apportion and pay or credit to its members dividends only out of that part of its surplus funds which represents net realized savings, net realized earnings, and net realized capital gains, all in excess of the surplus required by law to be maintained by the insurer.
(b) A dividend otherwise proper may be payable out of such savings, earnings and gains even though the insurer's total surplus is then less than the aggregate of contributed surplus remaining unpaid by the insurer.
(c) A domestic stock insurer may pay dividends to holders of its participating policies out of any available surplus funds.
(d) No dividend shall be paid which is inequitable or which unfairly discriminates as between classifications of policies or policies within the same classifications.