Final answer:
Goiter is caused by a deficiency of iodine (option C), leading to hypothyroidism symptoms like weight gain and reduced mental activity. It's prevented by consuming iodized salt or iodine supplements.
Step-by-step explanation:
Goiter is primarily caused by a deficiency of iodine (option C). This condition leads to the enlargement of the thyroid gland due to the body's inability to synthesize thyroid hormones T3 (triiodothyronine) and T4 (thyroxine). When the thyroid gland cannot produce enough thyroid hormone due to lack of iodine, the pituitary gland responds by releasing more Thyroid Stimulating Hormone (TSH), which causes the thyroid gland to grow larger in an attempt to produce more hormones. This compensatory mechanism leads to the development of goiter.
The symptoms you would expect from a goiter due to iodine deficiency include features of hypothyroidism, such as fatigue, weight gain, cold sensitivity, and reduced mental activity. Severe iodine deficiency during pregnancy can lead to cretinism in infants, characterized by intellectual disabilities, stunted growth, and other developmental issues. Prevention of goiter can be achieved through the regular consumption of iodized salt or iodine supplementation in areas where iodine deficiency is common.