题目

阅读理解She's awfully cute. That's what Marty Ginsburg thoughtwhen he met his fellow Cornell student Ruth Bader in 1950. Soon he noticedsomething else. He thought she was awfully smart, says their sonJames Ginsburg. Mom said Dad was the only boy who dated her, Jamessays, who cared that she had a brain. That brain, of course, would take her all the way to the SupremeCourt. But while the world knows about Ruth Bader Ginsburg-the second woman tobe appointed as U. S. Supreme Court justice-the story of the grand love affairbetween Ruth and Marty hasn't been publicly told until now. As Ruth beca18．已知f（x）=$\left\{\begin{array}{l}{x^{{2^{\;}}}}\\ π\\ 0\end{array}\right.$$\begin{array}{l}，{x＞0}\\，{x=0}\\，{x＜0}\end{array}$，则f[f （-3）]等于（　　）A．0B．πC．π2D．9