If μ is the refractive index and A is the angle of prism, then the angular dispersion produced is given as:

ẟ= (μ-1) A

Because the relative refractive index of glass with respect to water is small compared to the refractive of glass with respect to air, the dispersive power of the glass prism is more in air than that in water. So, option (B) is correct and then according to this explanation, option (A) and (C) are incorrect.

(D) Angle of prism A considered in the above formula does not affect the dispersive power much because generally its value is taken very small. So, option (D) is incorrect.