Dana Reeve,the Wife of Actor Christopher Reeve,died at a Young

Dana Reeve,the wife of actor Christopher Reeve,died at a young age from lung cancer,although she had never smoked.Her cancer was likely caused by

A) a germline mutation.
B) two somatic mutations in the same lung cell.
C) exposure to carcinogens.
D) stress from caring for her husband,who had a spinal cord injury.