The correct answer is: Iodine.
Nuclear accidents mostly release radioactive iodine into the atmosphere. Iodine is a naturally occurring element that is found in small amounts in the environment. It is also used in a variety of medical and industrial applications. When released into the atmosphere, radioactive iodine can be inhaled or ingested by people and animals. It can then be deposited in the thyroid gland, where it can cause cancer.
The other options are incorrect because they are not radioactive elements. Carbon, phosphorus, and sulfur are all non-radioactive elements that are found in the environment. They are not associated with nuclear accidents.
Here is a brief explanation of each option:
- Carbon is a non-metallic element that is found in all living things. It is the most abundant element in the universe, and it is the basis for organic chemistry. Carbon is not radioactive.
- Phosphorus is a non-metallic element that is found in bones and teeth. It is also used in fertilizers and pesticides. Phosphorus is not radioactive.
- Sulphur is a non-metallic element that is found in proteins and vitamins. It is also used in fertilizers and sulfuric acid. Sulphur is not radioactive.