**Core Concept**
The "satiety signal" for lipids refers to a hormone that signals the brain to stop eating due to sufficient lipid intake. This hormone plays a crucial role in regulating appetite and energy balance.

**Why the Correct Answer is Right**
The correct substance is Cholecystokinin (CCK). CCK is a peptide hormone released by the duodenum (the first part of the small intestine) in response to fat and protein ingestion. It acts on the central nervous system to stimulate feelings of fullness and decrease hunger. CCK binds to its receptors in the brain, specifically the area postrema, which is responsible for detecting toxins and hormones in the blood. This binding action triggers the sensation of satiety, reducing food intake and promoting weight loss.

**Why Each Wrong Option is Incorrect**
**Option A:** None given, as there was no answer provided in the prompt.
**Option B:** This option is not relevant to the context of lipid satiety signals.
**Option C:** This option is incorrect as it does not relate to lipid satiety signals.

**Clinical Pearl / High-Yield Fact**
Cholecystokinin (CCK) has a synergistic effect with other hormones like gastrin and secretin to regulate digestion and appetite. Its release is also stimulated by the presence of certain nutrients, including fats, proteins, and carbohydrates.

**Correct Answer:** CCK (Cholecystokinin).