What is an indication of Routh- Hurwitz criteria if the characteristic equation consists of only odd powers of 's' ?

What is an indication of Routh- Hurwitz criteria if the characteristic equation consists of only odd powers of 's' ?

a. Roots of characteristic equation are imaginary
b. Roots of characteristic equation are real
c. Both (a & b)
d. None.

Correct Answer : a. Roots of characteristic equation are imaginary

Explanation :

According to R-H application, even if characteristic equation possesses either even powers of 's', or only the odd powers of 's', then roots have only the imaginary terms despite of real terms.