A developer wants too use EL to invoke a function using S{my：bloof（“foof”）}. Which is always true？（）
- A The method invoked by this function must be statie.
- B The function class must implement the Function interface.
- C The expression is NOT a valid EL expression for invoking a function.
- D The function must be declared in a web.xml file using the element.
- E The function class must have a method with the signature：Void bloof （java.lang.Strings）