Final answer:
Triangle ABC was rotated about the origin. The rule that describes the rotation is RO, 360°.
Step-by-step explanation:
To determine the rule that describes the rotation of triangle ABC about the origin, we need to analyze the given options.
A rotation of 90° around the origin would not result in the same triangle, so option A can be eliminated. Similarly, a rotation of 180° would result in the triangle being flipped, so option B can be eliminated. A rotation of 270° would also result in a different triangle, so option C can be eliminated.
Therefore, the correct rule that describes the rotation of triangle ABC about the origin is Option D: RO, 360°.