First Name Email(Required) Which function is used to add a new filter callback function?(Required) add_filter add_action Why must a filter callback function always return a value?(Required) All hook functions must return something. Because Matt Mullenweg said so. The callback function won't change the filter value unless it returns something. Trick question, every hook function should echo something. Does WordPress output a "Read More" link automatically when listing posts?(Required) Yes No. Choose the best answerChoose the most accurate statement about hook callback function arguments below:(Required) All filters will have at least one argument, but actions may not have any arguments at all. Any filter callback function will only have one argument. Developers cannot specify exactly how many arguments a hook callback function should have Why is it unsafe to directly modify files in WordPress core or a theme/plugin you didn't write?(Required) There's no risk, live your life! Making changes to the code might upset the original developer who wrote them. You might make a mistake and break your whole site. Updates to the files you've changes will erase any customizations you've made.