A system has a complex conjugate root pair of multiplicity two or more in its characteristic equation. The impulse response of the system will be:

• A. A sinusoidal oscillation which decays exponentially; the system is therefore stable
• B. A sinusoidal oscillation with a time multiplier ; the system is therefore unstable
• C. A sinusoidal oscillation which rises exponentially ; the system is therefore unstable
• D. A dc term harmonic oscillation the system therefore becomes limiting stable