Which organ is primarily responsible for detoxifying harmful substances in the body?

The liver is primarily responsible for detoxifying harmful substances in the body due to its unique role in metabolism and biochemistry. It processes nutrients absorbed from the digestive tract and is essential for the metabolism of drugs and other chemicals. The liver converts toxins into safer substances that can be eliminated from the body, often through bile or urine.

This detoxification happens through various biochemical pathways, including oxidation, reduction, hydrolysis, and conjugation. The liver’s ability to filter blood and process these substances is crucial for maintaining homeostasis and protecting the body from potentially harmful compounds, such as alcohol, pollutants, and drugs.

While the kidneys also play a role in filtering waste products from the blood and regulating water and electrolyte balance, they primarily focus on excretion rather than the metabolic transformation that occurs in the liver. The stomach and intestines are primarily involved in the digestion and absorption of nutrients rather than detoxification. Thus, the liver's central role in detoxification makes it the correct answer.