Answer:
Option B
Explanation:
For constructive interference through a thin film in reflected ligh, thickness of film must be
t=(m+12)λ2n2
where, m=0,1,2,.....
and n2 = refractive index of medium (soap film) with given values, we get
t=λ4n2 ( tmin occurs with m=0)
= 532×10−94×1.33=100nm