Choice "B" is correct. In order for not-for-profit organizations to be financially interrelated as defined by FASB ASC 958-605, their relationship must share both characteristics: one organization must be able to influence the operating and financial decisions of the other AND have an ongoing economic interest in the net assets of the other.
Choice "c" is incorrect. Although the ability to influence operating and financial decisions is significant to determining if organizations are financially interrelated, the ability to influence must be coupled with an economic interest.
Choice "d" is incorrect. Although the economic interest is significant to determining if organizations are financially interrelated, the economic interest must be coupled with the ability to influence operating and financial decisions of the other organization.
Choice "a" is incorrect. Coincidence of coverage area is not relevant to the determination of financial interrelationship.