Not three from each era.
Not three of each type.
Not “some”, the later “some more”.
Not albums-songs.
Not groups-songs.
Not “These aren’t rock and roll, but they are still my favorite”.
Definitely not “I just can’t choose!”, which just means “Definitely not a thread I should bother posting in”.
Three, and just three, of your top rock and roll songs as you personally define “rock and roll”.
Thank you.
“Wish you were here”, Pink Floyd
“Kashmir”, Led Zep
“American Pie”, Don McLean
Subject to change of course.
Back in Black - AC/DC
Bohemian Rhapsody - Queen
A Day in the Life - The Beatles
“Nadine,” Chuck Berry
“Honky Tonk Women,” Rolling Stones
“That Mellow Saxophone,” Roy Montrell.
At this particular moment:
1 & 2: “My Generation” and “Magic Bus” from side two of the original Live At Leeds LP
3: “Space Station #5” from the first Montose album.
I was going to choose “The Long One” (“Because” > “The End”) from Abbey Road but I figured it would count as multiple songs.
Rick Derringer - “Rock and Roll, Hoochie Koo”
Beatles- “Revolution”
Rolling Stones- “Sympathy For The Devil”
Gimme Shelter, Whole Lotta Love. I’ll think about a third.
How strict is the rock and roll genre? Black Sabbath, strictly, is heavy metal. If allowed, maybe War Pigs.
Again, your definition.
Bohemian Rhapsody - Queen
Saturday Night’s Alright for Fighting - Elton John
Hey Jude - The Beatles
Blue Oyster Cult - Don’t Fear the Reaper
Meat Loaf - I’d Do Anything For Love (But I Won’t Do That)
The Who - Won’t Get Fooled Again
The Train Kept a-Rollin’ - Johnny Burnette Trio
The Witch - The Sonics
I Can See for Miles - The Who
Rosalita – Bruce Springsteen
Rocky Mountain Way – Joe Walsh
Music Must Change – The Who
Knocking at Your Back Door - Deep Purple
Possum Kingdom - Toadies
Detroit Rock city - Kiss
So far, nothing I wouldn’t to hear driving from Portland to Spokane in the middle of the night with the top down.
Won’t Get Fooled Again - The Who
Runaway - Bonnie Raitt
SOB - Nathaniel Ratcliff
Again, my definition, for those who care, is Rock and Roll songs that I’ll always pause and listen too, and almost always sing along:
“Money for Nothing” - Dire Straits
“Dream On” - Aerosmith
“Paint it Black” - Rolling Stones
Although that’s today’s answer. Because our OP demanded an answer right now. Moods are things, and in another thread, my answer could change. 
Somebody to Love, Queen
Somebody Told Me, The Killers
Lithium, Nirvana
Gimme Shelter - The Rolling Stones
Tie Your Mother Down - Queen
Rockaway Beach - The Ramones
Thunder Road, Bruce Springsteen
Like a Rolling Stone, Bob Dylan
Bad, U2
Back in the USSR - The Beatles
Black Dog - Led Zeppelin
Jessica - The Allman Brothers Band