24. Consider a soap film of thickness t and index of refraction n (>1)
suspending in air (index of refraction ~1). Light of wavelength λ is incident on
the soap normally. If the intensity of the reflection is 0 (destructive
completely), what is the maximum of 2t? (A) nt (B) 2t (C) 2nt (D) 4t (E) 4nt