**Core Concept**
Glucocorticoids are a class of steroid hormones that play a crucial role in maintaining normal blood glucose levels, particularly in the context of stress and fasting states. They act through intracellular receptors, which are distinct from the membrane-bound receptors of other hormone classes.

**Why the Correct Answer is Right**
Glucocorticoids, such as cortisol, are released in response to stress, including fasting and dehydration. Cortisol acts on its intracellular receptors, including the glucocorticoid receptor (GR), which is a ligand-activated transcription factor. Upon binding to cortisol, the GR translocates to the nucleus and regulates the expression of target genes involved in glucose metabolism, including gluconeogenesis and glycogenolysis. This leads to an increase in blood glucose levels, which is essential for maintaining energy homeostasis during periods of stress.

**Why Each Wrong Option is Incorrect**
* **Option A:** Insulin is a hormone that acts on membrane-bound insulin receptors, not intracellular receptors. While insulin is crucial for glucose metabolism, it is not the correct answer in this context.
* **Option B:** Aldosterone is a mineralocorticoid that regulates electrolyte balance and blood pressure, but it is not primarily involved in maintaining normal blood glucose levels.
* **Option D:** Growth hormone (GH) is a hormone that stimulates gluconeogenesis and lipolysis, but it does not act on intracellular receptors in the same way as glucocorticoids like cortisol.

**Clinical Pearl / High-Yield Fact**
Glucocorticoids, such as cortisol, are often used in clinical settings to treat conditions like adrenal insufficiency and to support patients during periods of stress or critical illness. However, long-term use of glucocorticoids can lead to side effects like osteoporosis, hypertension, and glucose intolerance.

**Correct Answer:** C. Cortisol