Which Statement Regarding Chemical Signaling Systems Is False

Multiple Choice

Which statement regarding chemical signaling systems is false?

A) Autocrine signals have an effect on the cells that secrete them.
B) Paracrine signals have an effect on nearby cells.
C) Signals carried by the circulatory system come primarily from the environment outside the organism.
D) A cell must have a receptor for a signal in order to bind to the signal.
E) A cell without a receptor for a signal is not a target cell for that signal.