Mary noticed a large, brown spot on her skin. She has been p…

Mary noticed a large, brown spot on her skin. She has been playing tennis in the sun for several years without sun protection. She reported the discovery to a friend, who told her to apply the ABCDE rule to determine whether or not she had malignant melanoma. Her friend told her that if her answer was “no” to the questions that were asked by the ABCDE rule, she had nothing to worry about. What is the ABCD rule and should she ignore the spot if her answers are negative?