An obtuse triangle is sometimes an example of a/an:I. scalene triangleII. isosceles triangleIII. equilateral triangleIV. right triangle A. I, II, or III B. II or III C. III or IV D. I or II

An obtuse triangle is a triangle where one of the angles is greater than 90 degrees.

I. Scalene triangle: A scalene triangle is a triangle that has all sides of different lengths. An obtuse triangle can be a scalene triangle if all its sides are of different lengths.

II. Isosceles triangle: An isosceles triangle is a triangle that has at least two sides of the same length. An obtuse triangle can be an isosceles triangle if one of its angles is greater than 90 degrees and two of its sides are of the same length.

III. Equilateral triangle: An equilateral triangle is a triangle where all sides are of the same length and each angle is 60 degrees. An obtuse triangle cannot be an equilateral triangle because all its angles are less than 90 degrees.

IV. Right triangle: A right triangle is a triangle where one of the angles is exactly 90 degrees. An obtuse triangle cannot be a right triangle because all its angles are either less than or greater than 90 degrees.

So, an obtuse triangle can sometimes be an example of a scalene triangle or an isosceles triangle. Therefore, the answer is D. I or II.