Use the Following to Answer Questions

Multiple Choice

Use the following to answer questions :
The way in which the velocity of an airplane is controlled can be thought of as an analogy for a negative-feedback control system in an organism.Suppose an airline pilot sets an aircraft's engines to produce a velocity of 450 mph,and measures that speed using an instrument on the outside of the plane.When another pilot reports turbulence ahead,the first pilot uses the throttle to change the velocity set point to 350 mph.
-According to this analogy,the throttle is

A) the control mechanism.
B) destabilizing.
C) initiating positive feedback.
D) an effector.
E) the controlled variable.