Which physiologic process allows hormones to exert influence upon some cells and not others?

receptor binding

Explanation:

Hormones are able to act specifically on target cells through receptor binding. This process enables target cells to react to a specific hormone only. The cells have hormone receptors within or on their surface which permits the specific hormone to act on it, thereby initiating a series of functions of the particular cell that has the hormone receptor. For example, thyroid receptors respond to thyroid-stimulating hormone.