[单选题]
At the first maxima on either side of thrry3o .cbs keikj8(g(*89vwse centr.rj 8miqw x 0hv-p5xv0al bright spot in a double-slit experiment, light from each opening arrivmrx.vvx08i j-5 wqh p0es
A. in phase.
B. $90^{\circ}$ out of phase.
C. $180^{\circ}$ out of phase.
D. none of the given answers
