The correct answer is option 2, Goitre.

Option 1, Arthritis, is not an iodine-deficiency disease. Arthritis is a condition that causes pain and inflammation in the joints, and it is not related to iodine deficiency.

Option 3, Glaucoma, is also not an iodine-deficiency disease. Glaucoma is an eye condition that damages the optic nerve and can lead to vision loss, and it is not caused by iodine deficiency.

Option 4, Pneumonia, is also not an iodine-deficiency disease. Pneumonia is an infection that causes inflammation in the lungs, and it is not related to iodine deficiency.

Goitre, on the other hand, is a condition that occurs when the thyroid gland in the neck becomes enlarged due to iodine deficiency. The thyroid gland needs iodine to produce thyroid hormones, and when there is not enough iodine in the diet, the gland tries to compensate by growing larger. Goitre can cause a variety of symptoms, including swelling in the neck, difficulty swallowing, and changes in thyroid hormone levels.