The indoor pollutant radon which is a radioactive gas causes

lung cancer
anemia
hormone disorder
cardiac arrest

The correct answer is A. lung cancer.

Radon is a radioactive gas that is found in the soil and can seep into homes through cracks and openings in the foundation. When radon is inhaled, it can damage the lungs and increase the risk of lung cancer.

Anemia is a condition in which the body does not have enough healthy red blood cells. This can cause symptoms such as fatigue, shortness of breath, and pale skin. Anemia is not caused by radon exposure.

Hormone disorders are conditions that affect the production or function of hormones. There is no evidence that radon exposure can cause hormone disorders.

Cardiac arrest is a sudden stop of the heart. It is a medical emergency that can be fatal. There is no evidence that radon exposure can cause cardiac arrest.

Radon is a serious health hazard, and it is important to take steps to reduce your exposure to it. You can do this by testing your home for radon, and by taking steps to fix any problems that are found. You can also reduce your exposure to radon by using a radon-reduction system in your home.