Which three are true about functions and procedures? (Choose three.)

A: The ACCESSIBLE BY clause can be used only for procedures. B: In a function, every execution path must lead to a RETURN statement. C: Both can have only constants as actual parameters for IN mode parameters. D: Both can be invoked from within SQL statements. E: In a procedure the RETURN statement cannot specify an expression. F: In a function every RETURN statement must specify an expression.