The correct option is (B) > √2.
Explanation:
For total internal reflection i > θ_{c} ......(1)
when θ_{c} is critical angle
sin θ_{c} = (1/η) i.e. η = (1 / sin θc)
i = 45°
hence 45° > sin ^{–1}(1/η) From (1)
sin 45° > (1/η)
(1 / √2) > (1/η) hence η > √2