The primary organ that changes toxic substances to non-toxic substances so that they can be eliminated from the body.

• A. Large intestine
• B. Liver
• C. Appendix
• D. Kidney

Answer: (B)

Detoxification and getting rid of toxic substances is mainly done by the liver. It metabolizes harmful compounds through two main steps: first, it changes the chemicals using enzymes (often adding or altering oxygen, hydrogen, or other groups), and then it attaches small, water‑soluble molecules to those modified substances. This process makes the toxins easier to dissolve in water, so they can be eliminated more readily. The finished products can be cleared by the kidneys in urine or sent into bile to be excreted in feces. The liver also receives blood from the gut, which helps it encounter and process toxins absorbed from the digestive system.

Other organs help with elimination but don’t perform this chemical transformation as their primary role. The kidneys are key for filtering waste from the blood, but they don’t usually metabolize toxins themselves. The large intestine mainly handles solid waste, and the appendix isn’t a detoxification center. That combination makes the liver the best answer for how toxic substances are converted into non-toxic, excretable forms.