[单选题]
If a wave from one slit of a Young's double slit experiment arr 1-jyoy1iuxy sj gv420ives at a po+2xham) (pb*nfw ttg ;3chxa -int on the screen one-half wavelength behind the wave from the other slit, which is observed at that poin+x)nfh (;2h p t *axamcbgtw-3t?
A. bright fringe
B. dark fringe
C. gray fringe
D. multi-colored fringe