Answer:
A. Iodine
Step-by-step explanation:
A goiter is an enlargement of the thyroid gland, a gland found at the bottom of the neck. Goiters are typically harmless, but can result in a cough or difficulty swallowing and/or breathing.
They can be caused by many different things. A major cause is from a deficiency, or lack of iodine a trace mineral that is vital for the producing thyroid hormones. Other causes include inflammation, pregnancy, cancer in the thyroid, autoimmune diseased and more.
Therefore, the correct answer is A: iodine.