Which of the following is the correct output for the following JavaScript code:

var grade='D';  
var result;  
switch(grade)  
{  
case'A':  
        result+="10";  
case'B':  
        result+=" 9";  
case'C':  
        result+=" 8";  
case 'D'  
result+=" 6";  
default:  
        result+=" 0";  
}  
document.write(result);