If gain margin and phase margin both are positive, then the system is said to be :

The correct answer is option 1):(Stable)

Concept:

• The stability of the control system is based on the relation between gain margin and phase margin as 

• Gain Margin (GM)	Phase Margin (PM	Nature
  Positive	Positive	Stable
  Zero	Zero	Marginally Stable
  Negative	Negative	Unstable

• Gain margin GM is defined as the negative of the magnitude in dB, at phase cross over frequency,

• The phase margin of a system is defined as: PM = 180° + ϕ_gc

​