A is for Ambassador-class starships of the 24th century.
B is for Bajoran Boobage.
C is for the Capellan star system.
D is for Dilythium Miners. For some reason they seem to think that it's 1875 and they're living in the 'Ancient West".
E is for the Enterprise-C, the only starship named Enterprise as of the late 24th century to have been commanded by a female captain.
F is for Federation Funny Farm.