Which of the following patients would be a candidate now for revaccination with PPSV23?
a. a 66-year-old woman who received the first dose of PPSV23 at 60 years of age
b. a 68-year-old man who received the first dose of PPSV23 at 64 years of age
c. a 71-year-old man who received the first dose of PPSV23 at 65 years of age
d. A 45-year-old woman without a spleen who received the first dose of PPSV23 at 42 years of age