I suggest 1 or 3 from my little experience with petunias. I have one small plant struggling in the shade of tomatoes and one intermingled with a melon on a trellis. Last year they did better, with lots of sun.

Because it is autumn, I believe you could get away with 1, 2 or 3 since the sunlight in September is much less intense than summer sunlight, temperatures are lower and daylength is shorter. If you put them in full consistent shade, they won't flower as well. I grow Laura Bush petunias (a unique petunia bred with native petunias in its heritage) in full sun to lightly dappled shade all summer in the heat. It loves the heat and just eats it up. It is almost like the hotter it gets, the more it blooms, and the leaves never yellow in the heat like those of pickier hybrid petunias do. This year, an heirloom petunia called "Exerta" performed almost as well in the heat/sunlight as Laura Bush. All other petunias I prefer to keep in full sun in spring and fall and in morning sun/afternoon shade or dappled shade in the summer. I generally don't grow any others except for Laura Bush and Exerta any more, though I used to grow a lot of the Wave petunias when we weren't having drought every single year.

The purchase was spontaneous, of course. Further research concludes these are probably hybrids. Good for trial. If these fit well with me, I'll look into ordering some true perennials.

Laura Bush
Exerta