[单选题]
At the first maxima on eith;jqc*/ +kjh khl/ir*ker side of the cenrd2r03wip07k oripu+ tral bright spot in a double-slit experiment, light from each 27 o3pr+wuirkdp ri00opening arrives
A. in phase.
B. $90^{\circ}$ out of phase.
C. $180^{\circ}$ out of phase.
D. none of the given answers
