假设变量sum=0和j=80都是int类型，则下列语句中的正确的是( ).

A．if (true)
System. out. println("true");
else;
B．if (5＜＞1)
System. out. println( "not equal" );
C．for (iht j=20;j＜＜50;j--)
System. out. println (j);
D．while (j＞＞=50)
sum +=j;
j--;