What will be written to the standard output when the following program is run？（）   public class Q03e4 {   public static void main（String args[]） {   String space = " "；   String composite = space + "hello" + space + space；   composite.concat（"world"）；   String trimmed = composite.trim（）；   System.out.println（trimmed.length（））；   }   }  

A. 5

B. 6

C. 7

D. 12

E. 13