A clear case of shell-shock.

Why is only "izūgan" accepted and not f.ex. "izūgas"? It's not clear who is afraid of turtles.

isnt every possibility right? I had all 6 conjugations of the verb sagon as possible solution

"qintra ..." which of the six options works? All of them!

For future readers: Previously there was a multiple choice exercise with this sentence. I misunderstood how those worked (I assumed you'd be given an English translation and a choice of Valyrian options), and so all provided answers were correct. That exercise has since been disabled.