**Core Concept**
In post-menopausal women, the decrease in estrogen levels leads to an increase in the production and secretion of other hormones to compensate for the hormonal imbalance. This hormonal shift affects various physiological processes, including bone metabolism, lipid profiles, and cardiovascular health.

**Why the Correct Answer is Right**
The hormone that shows an increase in post-menopausal women is **calcitriol**, the active form of vitamin D. This increase is due to the decreased levels of estrogen, which normally inhibits the production of calcitriol. As a result, the parathyroid glands secrete more parathyroid hormone (PTH), leading to increased calcitriol production. Calcitriol, in turn, stimulates osteoclast activity, contributing to the increased bone resorption observed in post-menopausal osteoporosis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the hormone **aldosterone** is involved in electrolyte balance and blood pressure regulation, not directly related to the hormonal changes in post-menopause.
* **Option B:** This option is incorrect because **growth hormone** levels do not significantly increase in post-menopausal women, and its role is more related to growth and development rather than the hormonal changes in menopause.
* **Option C:** This option is incorrect because **insulin** levels may actually decrease in post-menopausal women due to the decrease in insulin sensitivity, not increase.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the decrease in estrogen levels in post-menopause leads to an increase in bone resorption, which can be mitigated by hormone replacement therapy (HRT) or bisphosphonates. However, the increased calcitriol levels can also contribute to hypercalcemia, which should be monitored in post-menopausal women on HRT.

**Correct Answer:** C. Calcitriol