I’m stuck, thank you.

Unlike the others, the 'a' values aren't all correctly placed.
The a = -4 in the middle is correctly placed, since it's the only parabola that opens downward. This applies whenever a < 0.
The left and right items are incorrectly placed. The more narrow graph needs to have a = 1. The further 'a' is from zero, the more narrow the parabola.