It is, in many cases, our inflection point is a situation where our second derivative is equal to zero. And even then, we don't know it's an inflection point. It would be a candidate inflection point. We would have to confirm that our second derivative crosses signs, or switches signs, as we cross that x value. But here we can't find a situation where our second derivative is equal to zero. But we have to remind ourselves that other candidate inflection points are where our second derivative is undefined. And so he can't make this statement without seeing where our second derivative could be undefined.