About 23% of people who get their eyes examined are found to have a detached retina (the retina is piled away from the tissue at the back of the eye.) what is the probability of an ophthalmologist examining seven people until he finds the first patient who has a detached retina?

a. (0.23)^7
b. (0.23)^6(0.77)^1
c. (0.77)^7
d. (0.77)^6(0.23)^1
e. 1-(0.23)^6