A vertical soap film with index of refraction \(n = 1.33\) suspended in air (\(n = 1.00\)) drains under gravity, forming a wedge shape whose thickness increases from top to bottom. Monochromatic light of wavelength \(\lambda_0\) in air shines normally onto the film. As draining continues, a band at the very top of the film thins until its thickness \(t\) is much smaller than \(\lambda_0\) (\(t \ll \lambda_0\)). Which of the following correctly describes the appearance of this top region of the film and provides the correct physical justification?