A thin prism P1 with angle 4∘ and made from glass of refractive index 1.54 is combined with another thin prism P2 made from glass of refractive index 1.72 to produce dispersion without deviation. Find the angle of prism P2.
a. 5.33∘
b. 4∘
c. 3∘
d. 2.6∘