**Q. A system is said to be unstable if***- Published on 27 Nov 15***a.** None of the poles of its transfer function is shifted to the right half of s-plane

**b.** At least one zero of its transfer function is shifted to the right half of s-plane

**c.** At least one pole of its transfer function is shifted to the right half of s-plane

**d.** At least one pole of its transfer function is shifted to the left half of s-plane

**ANSWER: At least one pole of its transfer function is shifted to the right half of s-plane**