**Core Concept**
Sclerotherapy is a medical procedure used to treat varicose veins by injecting a sclerosing solution into the affected veins, causing them to close off and eventually disappear. The goal of sclerotherapy is to eliminate visible and palpable varicose veins, thereby improving the appearance and reducing symptoms.

**Why the Correct Answer is Right**
The correct answers are sclerosing agents used for sclerotherapy of varicose veins. **Polidocanol** (A) is a sclerosing agent used to treat varicose veins, spider veins, and hemangiomas. **Sodium tetradecyl sulfate** (B) is another sclerosing agent used for sclerotherapy of varicose veins. **Sodium morrhuate** (C) is a sclerosing agent derived from cod liver oil, used to treat varicose veins and spider veins.

**Why Each Wrong Option is Incorrect**
**Option D:** This option is a distractor because it does not belong to the class of sclerosing agents used for sclerotherapy of varicose veins.

**Clinical Pearl / High-Yield Fact**
It is essential to note that sclerotherapy is not suitable for all types of varicose veins, particularly those that are large, tortuous, or have significant reflux.

**Correct Answer: D.**