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

b
New  
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
 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} [\frac{n_{cladding}}{n_{core}} ]](https://tex.z-dn.net/?f=%5Ctheta_%7Bmax%7D%20%3D%2090%20-%20sin%5E%7B-1%7D%20%5B%5Cfrac%7Bn_%7Bcladding%7D%7D%7Bn_%7Bcore%7D%7D%20%5D)
        ![\theta_{max} = 90 - sin^{-1} [\frac{1.421}{1.497}} ]](https://tex.z-dn.net/?f=%5Ctheta_%7Bmax%7D%20%3D%2090%20-%20sin%5E%7B-1%7D%20%5B%5Cfrac%7B1.421%7D%7B1.497%7D%7D%20%5D)
       
Given from the question the the largest angle is  5°
Generally the refraction index of the cladding is mathematically represented as 
            
           