Why was Marilyn Vos Savant's calculation of having breast cancer given a positive mammogram test flawed?

a. Hubble Telescope sees a dime sized view of the universe which represents an accurate sample

b. John Hinkley was a lunatic

c. Fibonacci series appears everywhere in nature

d. Women who get mammograms have a higher probability of breast cancer than the random American and Marilyn used the random American probability in her calculation