If and then the number of rational roots of equation equals
Can't be determined.
As we learnt in
Nature of roots
If is a polynomial equation with rational coefficients then irrational roots always occur in pair.
Now,
As the sum of coefficients is 0, so x = 1 is a root. So one root is rational.
Now, since all coefficients are rational, and irrational root can occur in pairs only for such a case, and one root is rational (x=1), hence other root will also be rational.
Option (C)