Possibly a for the first. Candlemas is in February, the others in December, .
Possibly b for the second. a and c relate to the birth of Jesus. b is just a celebration of the season.
Rudolph.. Comet and Vixen were among the reindeer who normally pulled Santa's sleigh. If there hadn't been such a thick fog that night, Rudolph would never have got a look in.
Mark. Matthew and Luke tell of the birth of Jesus. The other Gospels start when Jesus was older.