Hi Kristina – I was also confused on this question and I dug into the ROADMAP:
When I was looking at this question, I went through the ROADMAP and was able to eliminate a and b as 4/5 quadriceps will not need KAFO. Even though ankle DF is weak, in function they don’t say anything about foot drop in swing. There’s also no mention of ankle PF spasticity causing knee hyperextension. I can rule out DF assist and PF stop with that last two points. The only item left is floor reaction AFO which is supported because there is excessive knee flexion in stance which can cause knee buckling – the floor reaction AFO will create a knee extensor moment to increase stability at the knee in stance.
I think the spasticity referred to in the ROADMAP for AFO is specifically for ankle PF spasticity. And it says severe ankle PF spasticity impacting foot placement at IC requires rigid AFO only. So if it’s not impacting foot placement I continue on the algorithm. Hope that helps!