Problem
What do the inflection points on a normal distribution represent? Where do they occur? What do the inflection points on a normal distribution represent? Choose the correct answer below. A. They are the points that mark the boundaries of the middle $50 \%$ of the area under the curve. B. They are the points at which the curve changes sign. C. They are the points at which the cumulative area under the curve is 0 and 1 . D. They are the points at which the curve changes between curving upward and curving downward.
Solution
Step 1 ：The inflection points on a normal distribution are the points at which the curve changes between curving upward and curving downward. This is a property of inflection points in general, not just for normal distributions. Therefore, the correct answer is D. This is a theoretical question and does not require Python code to solve.
Step 2 ：Final Answer: \(\boxed{\text{D. They are the points at which the curve changes between curving upward and curving downward.}}\)
