在 △ABC\bigtriangleup {ABC}△ABC 中,内角 A,B,CA,B,CA,B,C 所对的边分别为 a,b,ca,b,ca,b,c ,若 B=π3,b2=94acB = \frac{\pi }{3},{b}^{2} = \frac{9}{4}{ac}B=3π,b2=49ac ,则 sinA+sinC=\sin A + \sin C =sinA+sinC=A. 23913\frac{2\sqrt{39}}{13}13239 B. 3913\frac{\sqrt{39}}{13}1339 C. 72\frac{\sqrt{7}}{2}27 D. 31313\frac{3\sqrt{13}}{13}13313