A lab worker in Alaska develops a carcinoma of the skin. This particular ... ...

A lab worker in Alaska develops a carcinoma of the skin. This particular worker is very dedicated, and almost never leaves the lab. The tumor is most likely the result of:
(A) Excessive cigarette smoking by coworkers.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 13. Specialized Eukaryotic Cells and Tissues