Which statement about positive feedback regulation is accurate?

A. Positive feedback can generate responses that oscillate on and off as the activities or concentrations of the participating components rise and fall.
B. Positive feedback regulation can generate an abrupt, all-or-none response in which the cell moves from ignoring a signal to responding to it very strongly.
C. In positive feedback, a molecular switch enhances the response to a signal by activating a component that lies downstream in the pathway.
D. Positive feedback is rare in biological systems.
E. In positive feedback, a downstream component acts to inhibit an earlier component in the pathway to diminish the response to the initial signal.