A parallel beam of light\[(\lambda =5000\overset{o}{\mathop{A}}\,)\]is incident at an angle \[\alpha =30{}^\circ \]with the normal to the slit plane in YDSE. Assume that the intensity due to each slit at any point on the screen is \[{{I}_{0}}\]. Point O is equidistant from \[{{S}_{1}}\] and \[{{S}_{2}}\]. The distance between slit is 1 mm, then the intensity at

• A. O is \[3\,{{I}_{0}}\]
• B. O is zero
• C. a point 1 m below O is \[4\,{{I}_{0}}\]
• D. a point on the screen 1 m below O is zero