A is for Ardana, Federation world and the location of the legendary cloud city of Stratos.
B is for Boothby. Legendary groundskeeper of Starfleet Academy. Who offers help and advice to young promising cadets. However, I suspect that he's actually a Martian.
C is for Cheron, a class-M planet once inhabited by two humanoid races with differing bichromatic skin color patterns that eventually exterminated one another in prolonged wars fueled by racial hatred.