Final answer:
Hyperthyroidism is a condition in which the thyroid gland is overactive and is characterized by symptoms such as rapid and irregular heartbeat, heat intolerance, weight loss, goiter, and protruding eyes. Depressed thyroxine, heart intolerance, and weight loss are all indicative of hyperthyroidism, while rapid heart rate is commonly observed in this condition. Therefore, the correct answer is weight loss.
Step-by-step explanation:
Hyperthyroidism is a condition in which the thyroid gland is overactive. It is characterized by symptoms such as rapid and irregular heartbeat, heat intolerance, weight loss, goiter, and exophthalmia (protruding eyes). Depressed thyroxine, heart intolerance, and weight loss are all indicative of hyperthyroidism, while rapid heart rate is commonly observed in this condition. Therefore, the correct answer is d. Weight loss.