Afiber-optic cable (n = 1.53) is submerged in water (n = 1.33). predict whether light will be refracted or whether it will undergo total internal reflection if the angle of incidence is between 65° and 70°.

Total internal refraction occurs when a ray of light meets the following conditions. 
1. light falls from an optically dense material to a less dense material. 
2. The angle of incident in the denser media must be greater than the critical angle. 

In the case above the fiber-optic is optically denser than water. Since the light is incident to fiber-optic-water interface, then one condition is fulfilled.
Checking the other condition we carry out the calculation below;

n1sinФ1=n2sinФ2
where c ⇒critical angle  
1.53 sinc = 1.33 sin 90
sinc =0.86928
   c = 60.37° 

The angle of incident is (65°-70°) is greater than critical angle. 
With certainty, there would be no refraction. Total internal reflection would occur. 

Ithink it is letter b, i may be wrong but i think that is the answer

How is it possible that phylogenies based on sequences from nuclear genomes and organellar genomes (i.e., chloroplasts and mitochondria) from the same group of species yield phylogenetic trees with different branching orders?   answer :   the genome of the endosymbiont is more closely related to members of the group in which it originally evolved, while the nuclear genome of the engulfing organism has its own evolutionary trajectory.