Which of the following symptoms is typical of Hashimoto's thyroiditis?

Weight gain is a typical symptom of Hashimoto's thyroiditis, which is an autoimmune condition that leads to hypothyroidism, or an underactive thyroid. In this condition, the immune system attacks the thyroid gland, causing it to produce insufficient thyroid hormones. Since thyroid hormones are critical for regulating metabolism, their deficiency slows down metabolic processes, leading to weight gain. Individuals may experience fatigue, depression, and sensitivity to cold, alongside the weight gain, which further correlates with the overall decrease in metabolic activity due to low hormone levels.

The other options represent symptoms typically associated with other thyroid disorders or conditions. Heat intolerance, for example, is more characteristic of hyperthyroidism, where increased metabolism leads to an overproduction of thyroid hormones. Increased appetite also aligns with hyperthyroid conditions, where heightened metabolic activity can cause hunger. Ophthalmopathy, specifically associated with Graves' disease, involves eye changes that occur due to hyperthyroidism. Therefore, weight gain aligns directly with the effects of hypothyroidism caused by Hashimoto's thyroiditis.