Final answer:
Melanoma is the most deadly form of skin cancer because it is highly malignant and likely to spread to other parts of the body if not detected and treated early.
Step-by-step explanation:
Among the skin conditions presented, melanoma is the most deadly. This rare form of skin cancer originates in the melanocytes, which are located in the stratum basale of the epidermis. Unlike basal cell carcinoma, which is the most common type of skin cancer and rarely metastasizes, melanoma is notorious because it is highly malignant and likely to metastasize if not detected and treated early. Kaposi sarcoma is also a serious cancer, especially in immunocompromised individuals, such as those with AIDS, but the disease varies in severity.
Actinic Keratosis is a precancerous condition that can lead to squamous cell carcinoma if untreated. Squamous cell carcinoma is the second most common type of skin cancer and can metastasize, but is not as aggressive or deadly as melanoma.