**Core Concept**
Wood's light is a diagnostic tool used to visualize specific skin lesions and conditions under ultraviolet (UV) light. It emits a specific wavelength of UV-A light that causes certain substances to fluoresce, making them more visible.

**Why the Correct Answer is Right**
Wood's light is commonly used in dermatology to evaluate conditions such as vitiligo, albinism, and porphyrias. The UV-A light causes the skin to fluoresce, allowing for the visualization of these conditions. For example, in vitiligo, the affected skin areas may appear bright white under Wood's light due to the absence of melanin. This is because melanin absorbs UV light, and without it, the skin appears brighter under the UV-A light.

**Why Each Wrong Option is Incorrect**
**Option A:** Wood's light is not typically used for evaluation of skin cancers, as it is more useful for identifying benign conditions.
**Option B:** While Wood's light can be used for some infections, it is not the primary diagnostic tool for fungal or bacterial infections.
**Option C:** Wood's light is not used for evaluation of systemic diseases, as it is primarily a dermatological tool.

**Clinical Pearl / High-Yield Fact**
Wood's light can also be used to detect the presence of certain medications, such as tetracyclines, which can cause teeth or bones to fluoresce under UV light.

**Correct Answer:** D.