Monochromatic light is incident on 4 rectangular, parallel slits. The first principal maximum is observed at an angle θ to the direction of the incident light. The number of slits is increased to 8 each having the same width and spacing as the first 4.

Three statements about the first principal maximum with 8 slits are

     I.     the angle at which it is observed is greater than θ

     II.     its intensity increases

     III.     its width decreases.

Which statements are correct?

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III 

C