A vertical soap film (
= 1.33) suspended in air is illuminated at normal incidence by monochromatic light of vacuum wavelength \(\lambda_0 = 532\text{ nm}\). Near the top frame, the film forms a thin wedge whose thickness \(t\) increases linearly with downward vertical distance \(y\) from the top edge (\(y = 0\), where \(t \approx 0\)). A light sensor measures the reflected light intensity \(I\) as a function of position \(y\), producing the graph shown.

Which of the following claims correctly relates the features of the intensity graph to the physical properties of the film and incident light?