All three are/were junior HS phenoms.
PIng ran 9:43 indoor at age 13
Sclabas ran 9:41 indoor at age 13 (and now has a 9:23 outdoor PR at age 16)
McTighe ran 9:25 outdoor at age 13 in 2015, but did not register any marks in 2016 (is she still running?)
I'm not saying that all three will still be running at age 18, but I'm looking at who will have scored the best PR by the time they hit their 18th birthday (whether or not they are still running by then)