A swimmer under water (n=1.33) shines a narrow beam of light upward toward a flat glass plate (n=1.52) that is in contact with air (n=1.00). All interfaces are horizontal and parallel. What is the largest angle the beam can make with the normal in the water and still emerge into the air?
a) 41∘
b) 60∘
c) 49∘
d) 35∘