A thin prism $$P_1$$ with an angle $$6°$$ and made of glass of refractive index $$1.54$$ is combined with another prism $$P_2$$ made from glass of refractive index $$1.72$$ to produce dispersion without average deviation. The angle of prism $$P_2$$ is:

A

$$6°$$

B

$$1.3°$$

C

$$7.8°$$

D

$$4.5°$$