posted by Taylor .
The endocrine system..
A- affects only the reproductive system
B- releases substances into the bloodstream
C- competes with the nervous system to send signals
D- fights with the antibodies preoduced by the immune system
A is wrong. C depends on what "compete" means. D is wrong.
So B. Usually true, but not always. Sometimes substances are released just to stimulate adjacent cells.
So B is the best answer.