**Core Concept**
Grave's disease is an autoimmune disorder characterized by hyperthyroidism due to the production of thyroid-stimulating immunoglobulins (TSI), which stimulate the thyroid gland to produce excessive thyroid hormones. The key underlying principle in this condition is the overactivation of the thyroid gland, leading to an increase in thyroid hormone production.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of Grave's disease. In this condition, the thyroid gland is stimulated by TSI, leading to an increase in the production of thyroid hormones, including triiodothyronine (T3) and thyroxine (T4). The increased levels of these hormones can cause various systemic symptoms, including weight loss, heat intolerance, and palpitations. The correct answer is likely related to the effect of excessive thyroid hormone production on the body.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not directly relate to the pathophysiology of Grave's disease. While it is true that Grave's disease can cause weight loss, this is a symptom rather than a direct consequence of the disease process.

**Option B:** This option is incorrect because it is not specific to Grave's disease. Many conditions can cause tachycardia, and this option does not provide any information about the underlying cause of the condition.

**Option C:** This option is incorrect because it is not a direct consequence of Grave's disease. While Grave's disease can cause a range of systemic symptoms, this option does not provide any information about the specific effects of the disease on the body.

**Option D:** This option is incorrect because it is not a direct consequence of Grave's disease. While Grave's disease can cause weight loss, this is a symptom rather than a direct consequence of the disease process.

**Clinical Pearl / High-Yield Fact**
In Grave's disease, the production of thyroid-stimulating immunoglobulins (TSI) leads to the overactivation of the thyroid gland, resulting in an increase in thyroid hormone production. This can cause a range of systemic symptoms, including weight loss, heat intolerance, and palpitations.

**Correct Answer:** C.