A Tank Holds a Layer of Oil,1

A tank holds a layer of oil,1.70 m thick,which floats on a layer of syrup that is 0.74 m thick.Both liquids are clear and do not intermix.A ray,which originates at the bottom of the tank on a vertical axis,crosses the oil-syrup interface at a point 0.90 m from the axis.The ray continues and arrives at the oil-air interface,2.00 m from the axis and at the critical angle.In the figure,the index of refraction of the oil is closest to:

A) 1.84
B) 1.82
C) 1.80
D) 1.86
E) 1.88