36. A plane wave of monochromatic light is incident on an opaque metal sheet with four equally-spaced narrow slits. If the incident angle is slanted so that φ = nπ/2 is the phase difference between adjacent slits, and n is an integer. The center line at a far away screen parallel to the sheet is:
(A) a bright line
(B) a dark line
(C) half way between a bright line and a dark line
(D) a major bright line if n is a multiple of 4 and a minor bright line otherwise
(E) a bright line if n is a multiple of 4 and a dark line otherwise.