Question

Which type of skin cancer is the rarest and most deadly?

Answer 1

Malignant melanoma.

Explanation:

There are three major types of skin cancers: basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma. The first two skin cancers are grouped together as non-melanoma skin cancers. Other unusual types of skin cancer include Merkel cell tumors and dermatofibrosarcoma protruberans.

A small but significant number of skin cancers are malignant melanomas. Malignant melanoma is a highly aggressive cancer that tends to spread to other parts of the body. These cancers may be fatal if not treated early.

More details, types, prevention and treatment:
https://www.webmd.com/melanoma-skin-cancer/guide/skin-cancer