When the magnitude of (AoL ) ( ) = 0dB, state the condition at which system become stable?

When the magnitude of (AoL ) ( ) = 0dB, state the condition at which

1.	When the magnitude of (A_oL ) ( ) = 0dB, state the condition at which system become stable?
A.	Phase angle is > -180<sup>o</sup>
B.	Phase angle is < -180<sup>o</sup>
C.	Phase angle is > +180<sup>o</sup>
D.	Phase angle is < +180<sup>o</sup>
Answer» B. Phase angle is < -180<sup>o</sup>