Which statements concerning the value of a member variable are true， when no explicit assignments have been made？（）  

• A、The value of an int is undetermined.
• B、The value of all numeric types is zero.
• C、The compiler may issue an error if the variable is used before it is initialized.
• D、The value of a String variable is "" （empty string）.
• E、The value of all object variables is null.