If a question states that the graph of f'(x) crosses the x axis at x=5 , then is x=5 an inflection point of f(x) , is x=5 an inflection point of...

If a question states that the graph of f'(x) crosses the x axis at x=5 , then is x=5 an inflection point of f(x) , is x=5 an inflection point of f'(x) , is x=5 a critical number of f'(x). I need to pick one choice of these and defend it.

Thanks