What type of skin cancer is most directly attributable to sun exposure or chronic irritation?

Squamous cell carcinoma is the type of skin cancer that is most directly associated with sun exposure and chronic irritation. This form of skin cancer typically arises in areas that have been exposed to the sun, such as the face, ears, neck, and the back of the hands. Chronic irritation, from factors such as persistent inflammation or exposure to certain chemicals, can also lead to the development of squamous cell carcinoma.

The key characteristic of squamous cell carcinoma is its connection to actinic keratosis, a condition caused by long-term sun exposure that results in rough patches on the skin, which can progress to cancer over time. Consequently, individuals with significant sun damage or those who have undergone repeated sunburns are at increased risk for this type of cancer.

By understanding the relationship between squamous cell carcinoma and sun exposure, it becomes clear why this option is the best choice for the question posed.