**Core Concept**
Peptide hormones are a class of hormones composed of short chains of amino acids, which are linked together by peptide bonds. These hormones are produced by various endocrine glands, including the pituitary gland, thyroid gland, and pancreas. They play crucial roles in regulating various physiological processes, such as growth, metabolism, and electrolyte balance.

**Why the Correct Answer is Right**
The correct answer is a peptide hormone because it is a short chain of amino acids linked by peptide bonds. Peptide hormones are synthesized by ribosomes and then secreted by the endocrine glands. They bind to specific receptors on target cells, triggering various cellular responses. For example, insulin, a peptide hormone produced by the pancreas, regulates blood glucose levels by stimulating glucose uptake in cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a steroid hormone, which is a different class of hormones that are derived from cholesterol and have a steroid backbone.
**Option B:** This option is incorrect because it is a catecholamine, which is a type of hormone that is derived from the amino acid tyrosine and has a different structure and function than peptide hormones.
**Option C:** This option is incorrect because it is a thyroid hormone, which is a type of hormone that is derived from the amino acid tyrosine but has a different structure and function than peptide hormones.

**Clinical Pearl / High-Yield Fact**
Peptide hormones are often inactivated by proteolytic enzymes, which break down the peptide bonds between amino acids. This is why peptide hormones have a relatively short half-life compared to other types of hormones.

**Correct Answer: C. Insulin.