题目

阅读理解 Perhaps there is no sport in the world moreconnected to sneakers than basketball. Many NBA players wear them to sendimportant messages and showcase their personalities on court. And now, thanks to a new policy, the NBA willstrengthen its status as the most stylish sports league in the world. When the2018-2019 NBA season kicked off in October, the NBA lifted its colorrestrictions on players' sneakers. It is the first time in the league's 72-yearhistory that it has allowed shoes to be of any color a player likes, as long asno reflective(反光的) material is included. In the past, 椭圆＋＝1(a>b>0)的左顶点为A，左、右焦点分别为F1、F2，D是它短轴上的一个顶点，若，则该椭圆的离心率为(　　) A.                                                             B.  C.                                                             D.