A ray of light is incident from a denser to a rarer medium . The critical angle for total reflection is $\;\theta_{iC}\;$ and the Brewster's angle of incident is $\;\theta_{iB}\;$, such that $\;\large\frac{sin \theta_{iC}}{sin \theta_{iB}}=\eta= \normalsize 1.28\;$ .The relative refractive index of the two media is :

Question

$(a)\;0.2\qquad(b)\;0.4\qquad(c)\;0.8\qquad(d)\;0.9$