**Core Concept**
Orphan drugs are medications designed to treat rare diseases or conditions that affect a small percentage of the population. These drugs are often developed to address unmet medical needs and may have limited market potential due to their rarity.

**Why the Correct Answer is Right**
Orphan drugs typically receive financial incentives, such as tax credits and grants, to encourage their development and marketing. This support is crucial in covering the high costs associated with researching and manufacturing these drugs. The Orphan Drug Act (ODA) of 1983 in the United States and similar laws in other countries aim to facilitate the development of orphan drugs by providing these incentives.

**Why Each Wrong Option is Incorrect**
**Option B:** This option is incorrect because while orphan drugs may have a niche market, they are not necessarily more expensive than non-orphan drugs. In fact, many orphan drugs are priced competitively due to the financial incentives they receive.
**Option C:** This option is incorrect because while orphan drugs are indeed developed for rare conditions, they are not solely used for cosmetic or aesthetic purposes.

**Clinical Pearl / High-Yield Fact**
It's essential for physicians to be aware of the orphan drug designation and its implications for patient care. This includes understanding the potential financial incentives and the unique challenges associated with developing and marketing these drugs.

**Correct Answer:** D.