**Core Concept**
The movement of water-insoluble substances in the body is primarily determined by the process of **micelle formation** and the subsequent role of **lipoproteins** in their transport. This process involves the formation of lipid-water interfaces that facilitate the movement of non-polar substances across biological membranes.

**Why the Correct Answer is Right**
The movement of water-insoluble substances, such as fats and fat-soluble vitamins, is largely dependent on the formation of micelles. Micelles are spherical structures composed of a hydrophobic core and a hydrophilic surface, allowing them to solubilize non-polar substances in an aqueous environment. Lipoproteins, such as chylomicrons and very-low-density lipoproteins (VLDL), play a crucial role in the transport of these substances through the bloodstream, facilitating their delivery to target tissues.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the primary mechanism of movement for water-insoluble substances. While the liver does play a role in the metabolism of these substances, it is not directly responsible for their movement.
* **Option B:** This option is incorrect because it refers to the movement of water-soluble substances, which is primarily facilitated by diffusion and active transport mechanisms.
* **Option C:** This option is incorrect because it refers to the movement of substances across cell membranes, which is a different process altogether. While cell membrane transport is an important aspect of substance movement, it is not the primary mechanism for water-insoluble substances.

**Clinical Pearl / High-Yield Fact**
The formation of micelles is an essential process for the movement of water-insoluble substances in the body. Understanding this process is crucial for appreciating the role of lipoproteins in lipid metabolism and the transport of fat-soluble vitamins.

**Correct Answer: C. Lipoproteins. Micelle formation and lipoproteins facilitate the movement of water-insoluble substances in the body.**