**Core Concept**
The question is testing the student's knowledge of the chemical properties of drugs, specifically those containing sulfhydryl groups. Sulfhydryl groups are crucial in the pharmacological activity of certain drugs, particularly those that contain two such groups.

**Why the Correct Answer is Right**
Drugs with two sulfhydryl groups are known as dithiothiones. These compounds exhibit antioxidant properties and are often used in the treatment of Wilson's disease, a genetic disorder characterized by excessive copper accumulation in the liver. The sulfhydryl groups in these compounds form a covalent bond with copper, facilitating its excretion from the body.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify a drug with two sulfhydryl groups.
**Option B:** This option is incorrect as it does not accurately describe a drug with two sulfhydryl groups.
**Option C:** This option is incorrect as it does not specify a drug with two sulfhydryl groups.

**Clinical Pearl / High-Yield Fact**
Dithiothiones, such as penicillamine, are used in the treatment of Wilson's disease due to their ability to form a covalent bond with copper, facilitating its excretion from the body.

**Correct Answer: D. Penicillamine**