15.已知双曲线C:x2a2−y2b2=1(a>0,b>0)C:\frac{x^2}{a^2}-\frac{y^2}{b^2}=1(a>0,b>0)C:a2x2−b2y2=1(a>0,b>0),点BBB的坐标为(0,b)(0,b)(0,b),若CCC上的任意一点PPP都满足∣PB∣⩾b\vert PB\vert \geqslant b∣PB∣⩾b,则CCC的离心率取值范围是((( )))