对于Map("book" -> 5, "pen" -> 2).map(m => m._1 -> m._2 * 2)的结果，下面哪个是正确的？

A、Map("bookbook" -> 5, "penpen" -> 2);
B、Map("bookbook" -> 10, "penpen" -> 4);
C、Map("book" -> 10, "pen" -> 4);
D、Map("book" -> 5, "pen" -> 2 ,"book" -> 5, "pen" -> 2)