Parabola related question

regmat.com/quizzes/quiz/timed-quant-practice-medium-section-2-sample-test-3

in question 8, if i convert the parabola question into y=a(x-h)+ k, where (h,k) is vertex then the vertex turns out to be (b/2,8). Then b can take all vales mentioned in the question and it will still not touch x axis, if I draw a graph…

What’s wrong with this understanding?

Can you post the question as an ss or something?

Also it’s y = a(x - h)^2 + k