Which sentence is punctuated correctly?

A. Annie Peck Smith, did not let old age stop her from enjoying her favorite hobby, mountain climbing.

B. Smith climbed her final mountain, Mount Madison in New Hampshire, at the age of 82.

C. In her seventies, she spent seven months flying over South America, to research a book.

D. She set out on a world tour at 84, but became ill, and died, before she could complete the trip.