Correct Answer - C
No. of waves `= ("Thickness of medium")/("Wavelength")`
Given that same number of waves for glass and water
i.e., `(4)/(lambda_(g)) = (5)/(lambda_(w)) :. (lambda_(g))/(lambda_(w)) = (4)/(5)`
`mu_(w) = (lambda_(a))/(lambda_(w))` & `mu_(g) = (lambda_(a))/(lambda_(g)) :. (mu_(g))/(mu_(w)) = (lambda_(w))/(lambda_(g))`
Thus, `mu_(g) = (lambda_(w))/(lambda_(g)) mu_(w) = (5)/(4) xx (4)/(3) = (5)/(3)`