**Core Concept**
Ringworm infection, also known as tinea corporis, is a superficial fungal infection caused by dermatophytes that affect the outermost layer of the skin. It is characterized by a circular, itchy rash with clear centers, often accompanied by scaling and inflammation.

**Why the Correct Answer is Right**
The correct answer is due to the pathophysiology of ringworm infection, which involves the invasion of dermatophytes into the stratum corneum of the skin. Dermatophytes, such as Trichophyton rubrum and Microsporum canis, produce keratinases that break down keratin, leading to the formation of the characteristic ring-shaped lesions. The immune response to the infection results in inflammation, itching, and scaling.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because ringworm infection is not caused by bacterial invasion, but rather by fungal infection.
**Option B:** This option is incorrect because ringworm infection is not caused by viral infection, but rather by fungal infection.
**Option C:** This option is incorrect because ringworm infection is not caused by parasitic infection, but rather by fungal infection.

**Clinical Pearl / High-Yield Fact**
It's essential to note that ringworm infection can be spread through direct contact with an infected person or animal, contaminated soil or objects, and through fomites. Effective treatment involves the use of antifungal medications, such as topical creams or oral tablets, and good hygiene practices.

**Correct Answer: D. Dermatophytes.**