**Core Concept**
The question is testing the concept of drug distribution and accumulation in the body, specifically in muscles. This is an important aspect of pharmacokinetics, which involves the study of how drugs are absorbed, distributed, metabolized, and excreted by the body.

**Why the Correct Answer is Right**
The correct answer is a drug that is known to accumulate in muscles due to its large molecular size and low lipid solubility. This allows it to be taken up by muscle cells, where it can be stored for extended periods. One such drug is **D. Lanugo (Lanoxin)**, which is a cardiac glycoside used to treat heart failure. Lanoxin is deposited in muscles due to its large molecular size and low lipid solubility, allowing it to be taken up by muscle cells.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not a drug that is known to accumulate in muscles. **Digoxin** is a cardiac glycoside, but it is primarily excreted by the kidneys.
* **Option B:** This option is incorrect because it is not a drug that is known to accumulate in muscles. **Furosemide** is a loop diuretic that acts on the kidneys to increase urine production.
* **Option C:** This option is incorrect because it is not a drug that is known to accumulate in muscles. **Amlodipine** is a calcium channel blocker used to treat hypertension and angina.

**Clinical Pearl / High-Yield Fact**
It's worth noting that drugs that accumulate in muscles can cause muscle weakness, fatigue, or other muscle-related side effects. This is an important consideration when prescribing medications that may accumulate in muscles, such as Lanoxin.

**Correct Answer:** D. Lanoxin is deposited in muscles.