Correct Answer - c.
`2mutheta=mu(2^(@))rArr theta=1^(@)`
`alpha=theta-gamma`
`beta(3mu)=(2mu)alpha rArr beta=(2)/(3)(theta-gamma)`
Angle made by emergent ray with optic axis is
`=beta+gamma`
`=(2)/(3)(theta+gamma)+gamma=(2)/(3)theta-(gamma)/(3) cong (2)/(3)xx1^(@)=((2)/(3))^(@)`
[because `gamma cong 0^(@)` for thin lens]
![image](https://learnqa.s3.ap-south-1.amazonaws.com/images/16104072637829927441610407263.png)