[单选题]
At the first minima on either ud;fgj)h yg,0h ia5t rwd,ojt,(.d -iside of5 vug 7mtmq(n: the central bright spot in a double-slit experi: 7tqumnm(5vg ment, light from each opening arrives
A. in phase.
B. $90^{\circ}$ out of phase.
C. $180^{\circ}$ out of phase.
D. none of the given answers
