After Light from a Source Passes Through Two Slits,a First-Order

Multiple Choice

After light from a source passes through two slits,a first-order bright spot is seen on the wall at point P.Which distance is equal to the wavelength of the light?

A) the extra distance one beam must travel
B) the distance between beams as they leave the slit
C) the distance of point P from the central point of the interference pattern
D) the distance between slits