A is for Antares-class cargo vessels of the 23rd and 24th centuries.
B is for Barbara Luna until she says it's not.
C is for Carl Spock.
D is for Denobulan first contact with Earth humans, which happened at some unspecified point between the years 2063 and 2150.
E is for Enterprise. USS Enterprise, CVN-65. Retired and in need of saving.
F is for Ferengi first contact with Earth humans, which happened in the year 2151 even though humans didn't know the name of the species at the time of that initial encounter.