Home › WordPress UpWork Test Answers What is the function of add_filter in WordPress? By · Tuesday, June 20, 2017 What is the function of add_filter in WordPress? Answers: 1. It registers a filter for a tag. 2. It removes line breaks from the pages list. 3. It is a companion function to apply_filters(). 4. All of the above. WordPress UpWork Test Answers GA Gaurav Arora, Digital Media Lead. 10+ years running paid media and tracking for brands in the USA, UK and Canada.