The correct answer is option 1: Fluorine. Fluorine is essential for preventing dental caries, also known as tooth decay. Fluoride is a mineral that helps to prevent cavities by strengthening the tooth enamel. It works by remineralizing the weakened enamel and preventing the growth of harmful bacteria in the mouth. Fluoride can be obtained from various sources, including fluoridated water, toothpaste, mouthwashes, and professional fluoride treatments.

Option 2: Iodine is not essential for preventing dental caries. Iodine is a mineral that is necessary for the production of thyroid hormones and is primarily found in iodized salt and seafood.

Option 3: Iron is not essential for preventing dental caries. Iron is a mineral that is important for the production of hemoglobin, the protein in red blood cells that carries oxygen throughout the body. Iron is primarily obtained from dietary sources such as meat, lentils, and spinach.

Option 4: Zinc is not essential for preventing dental caries. Zinc is a trace mineral that is important for various bodily functions, including immune system support, wound healing, and proper growth and development. Zinc is found in foods such as meat, shellfish, and legumes.

Overall, fluoride,