**Core Concept**
Penile carcinoma is a type of cancer that affects the penis, and its most common form is related to the type of cells involved. The underlying principle being tested here involves the histopathological classification of penile cancers.

**Why the Correct Answer is Right**
The most common type of penile cancer is squamous cell carcinoma, which arises from the squamous cells of the penile epithelium. This type of cancer is often linked to **human papillomavirus (HPV)** infection and poor genital hygiene. The mechanism involves the infection leading to malignant transformation of the squamous cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because, although other types of cancer can occur in the penis, they are less common than squamous cell carcinoma.
**Option B:** Similarly, this option is incorrect as it does not represent the most common type of penile cancer.
**Option D:** This option is also incorrect for the same reason, not being the predominant form of penile carcinoma.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **squamous cell carcinoma** is the most common type of penile cancer, especially in older men, and its prevention is closely linked to **HPV vaccination** and good genital hygiene practices.

**Correct Answer:** D. Squamous cell carcinoma.