Which of the following conditions is associated with a deficiency of iodine?

A deficiency of iodine is primarily associated with goiter, which is the correct answer. Iodine is an essential nutrient that plays a crucial role in the synthesis of thyroid hormones, which are vital for regulating metabolism and overall growth and development. When the body lacks adequate iodine, the thyroid gland enlarges as it tries to compensate for the insufficient hormone production, leading to the formation of a goiter. This enlargement is often visible as a swelling in the neck.

Other conditions listed, such as rickets, anemia, and poor teeth, are not directly related to iodine deficiency. Rickets is primarily caused by a deficiency of vitamin D, calcium, or phosphate, which affects bone health and growth. Anemia often results from a lack of iron, vitamin B12, or folate, affecting the body's ability to produce healthy red blood cells. Poor teeth can be attributed to various factors including poor dental hygiene or deficiency in nutrients like calcium and vitamin D, rather than iodine specifically. This context reinforces the unique association of goiter with iodine deficiency.