Iodized salt is a mixture of potassium iodide and common salt. Potassium iodide is a compound that contains iodine, which is an essential nutrient for the human body. Common salt, also known as table salt or sodium chloride, is a compound made up of sodium and chlorine.

In the production of iodized salt, potassium iodide is added to common salt in order to increase the iodine content. This is done to address iodine deficiency, which is a common health issue in many parts of the world. Iodine is important for the proper functioning of the thyroid gland and for the production of thyroid hormones, which regulate metabolism.

It is important to note that iodized salt is different from iodine salt. Iodine salt is a different compound where molecular iodine is combined with common salt. Iodized salt, on the other hand, contains potassium iodide and common salt, which makes it a more stable and safer source of dietary iodine.

Therefore, option 1 is the correct answer as it accurately describes iodized salt as a mixture of potassium iodide and common salt.