程序:
class TestReference{ public static void main(String[] args){
int x=2;
TestReference tr = new TestReference();
System.out.print(x);
tr.change(x);
System.out.print(x);
}
public void change(int num){
num = num + 1; } }
程序運行后的輸出是哪項?()
A. 23
B. 21
C. 22
D. 編譯錯誤