下面哪个代码片段是错误的? A. package mypackage; public class Rectangle{//doing something…} B. import java.io.*; package mypackage; public class Rectangle{//doing something…} C. import java.io.*; class Circle{//doing something…} public class Rectangle{//doing something…} D. import java.io.*; import java.awt.*; public class Rectangle{//doing something…}