The services of business brokers or business opportunity brokers may be authorized by the appropriate Assistant Administrator in lieu of or in addition to real estate brokers for the sale of businesses as a whole, including goodwill and chattel, when:

(a) The primary use of the structure included in the sale is other than residential;

(b) The business broker is duly licensed by the respective state; and

(c) The primary function of the business is other than farming or ranching.