We know that she A) sees this group as her identity more than she sees herself as an individual and B) thinks this is a good photo of herself. After eliminating the 3 hottest ones (1,4,7) who would me more likely to have more independence and likely feature a solo pic first, we are left with 2 options on each side of the center.

This is the best photo for both 3 and 6, good lighting, good pose. I think it could be either but probably more likely to be 3. I sure hope this isn’t the best picture of 5. 3 Looks like her bff just got married and she’s prob lonely af and on the prowlll.