Answer is a. Contained very small amounts of dioxin.
Agent Orange contained amounts of a type of dioxin called TCDD which is highly persistent chemical that lasts in environment for many years. Studies have proven that dioxin is highly toxic and known to be a cancer-causing agent. Short-term exposure to it can cause skin darkening, liver problems and skin disease called chloracne. Also it was linked to type 2 diabetes, nerve disorders, and heart disease.