Which of the following statements is true about a scalene triangle?

A scalene triangle is characterized by having all sides and angles of different lengths and measures. This definition sets it apart from other types of triangles, such as isosceles triangles, which have at least two equal sides and angles, and equilateral triangles, where all sides and angles are equal. Therefore, the statement that all sides and angles are different is fundamentally correct and accurately describes the properties of a scalene triangle.

Understanding the unique features of scalene triangles helps in recognizing their distinctions from other triangle categories. For example, the option that states two sides are equal in length pertains to isosceles triangles. Similarly, stating that a triangle has one right angle could describe a right triangle but does not apply to scalene triangles specifically. Lastly, the description of having at least two congruent angles aligns with isosceles and isosceles right triangles, which again is not applicable to scalene triangles. Thus, the uniqueness of a scalene triangle is captured well in the assertion that all sides and angles are different.