You have a test group, whereby rats have been exposed to increasing concentration of a toxicant via ingestion ford toxincant WAS and FD and inhalation of toxicant PHM. The following graph was plotted. Please use this graph to answer the following questions. What is the threshold value for Toxin FD? (# units) Dose-Response Relationship for Toxin WAS, FD and PHM 100% 90% 80% 70% 60%% Response 50% 40% 30% 20% 10% 0% 10 mg 20 mg 25 mg 30 mg Toxin WAS Toxin FD Toxin PHM Dose of Toxin