Which of the following statements is accurate?

Explanation

Option A is incorrect because the uniformity coefficient measures the range of particle sizes, not the shape of the distribution curve. Option B is wrong since a well-graded soil typically has a uniformity coefficient and coefficient of curvature that differ significantly from unity. Option C is false because well-graded soils contain a wide variety of particle sizes rather than particles of nearly the same size. Therefore, the correct choice is D, indicating that none of the given statements are true.