A. Missing Spectra
B. Absent Spectra
C. End Spectra
D. Emission Spectra
This question was posed to me at a job interview.
My doubt stems from Fresnel and Fraunhofer Diffraction in division Diffraction of Engineering Physics II
The explanation: In Double Slit Fraunhofer Diffraction, there are certain angles where the interference maxima and Diffraction minima overlap. These orders of interference pattern are missing in the pattern. It is known as Absent Spectra.