My first choice is: option Z (all of the above!)
But I'll go with the most recent partial songs that I've heard....
Sweet Home Alabama ~ Lynyrd Skynyrd
American Woman ~ Guess Who
Stairway to Heaven ~ Led Zeppelin
Bohemian Rhapsody ~ Queen
Runnin' With the Devil ~ Van Halen
Hopefully this both helps within this poll, and will probably also show how many of the same songs have received a lot of airtime and for many years, too. I'll also say that many of these songs are excellent, long time favorites, which may be both why they have been played a lot over the years, as well as continue to get so much airtime, now.
However, imo, the playing of these songs for many years and also currently is bound to lead to probably many people either already burned out with hearing one or more over that time period, but also having another affect with not wanting to hear some of these classic songs, too.
I'd find it extremely difficult to be a DJ on a classic rock radio station, and mostly only having the rather limited selections/playlists that are allowed by the station managers and their sponsers.