Which filter would Liu adjust if they want to target a complementary product to the one in their ad?

To target complementary products, Liu should use the "expanded" filter. This filter broadens targeting to include products that are frequently bought together with the advertised product or are related in some way, making it ideal for reaching customers interested in complementary items. The "category" filter would target all products within a specific category, which might be too broad and include many non-complementary items. The "exact" filter would only target the specific product ASINs listed, which is too narrow for finding complementary products and is typically used for defensive targeting or specific product promotion.