The most important structures to receive external stimulus are (1)__ and the system of these organs is called (2)____.

The most important structures to receive external stimulus are (1)__ a

1.	The most important structures to receive external stimulus are (1)__ and the system of these organs is called (2)____.
Answer» The most important structures to receive external stimulus are (1)__ and the system of these organs is called (2)____.