Complete Question
The complete question is shown on the first uploaded image
Answer:
a

b
New

Step-by-step explanation:
From the question we are told that
The refractive index of the core is

The refractive index of the cladding is

Generally according to Snell's law

Where
is the largest angle a largest angle a ray will make with respect to the interface of the fiber and experience total internal reflection
![\theta_(max) = 90 - sin^(-1) [(n_(cladding))/(n_(core)) ]](https://img.qammunity.org/2021/formulas/physics/college/czt27ob4hyc17bsirhb4h9za3ea7tm37rk.png)
![\theta_(max) = 90 - sin^(-1) [(1.421)/(1.497)} ]](https://img.qammunity.org/2021/formulas/physics/college/jvm83tkjp3jcvfj1ydhvevdc02uh0d007f.png)

Given from the question the the largest angle is 5°
Generally the refraction index of the cladding is mathematically represented as

