Which List Includes Only Those Factors Necessary for a Hormone

Which list includes only those factors necessary for a hormone to be effective?

A) hormone producing gland, a duct through which hormones can flow, proper receptors at target organ
B) hormone producing cells with membrane channels through which the hormone can be released, proper receptors in the bloodstream and a target organ
C) hormone producing cells with membrane channels through which the hormone can be released, access to the bloodstream and receptors on a target organ
D) hormone producing gland that is controlled by another hormone producing gland, a duct through which hormones can flow, a clear connection to the target organ