The correct answer is D) The presence of small cracks in the races. As rolling element bearings are subjected to repeated cycles of stress over time, fatigue failure can occur. The first evidence of the beginnings of this fatigue failure is the presence of small cracks in the bearing races, which are the inner and outer rings that the rolling elements (e.g., balls or rollers) travel along. These small cracks in the races are the initial signs of the fatigue process starting, before more advanced failure modes like spalling or pitting become evident. The other options are incorrect because they represent later stages of the fatigue failure process (discoloration, metallic particles) or are not the first evidence (cracks in the rolling elements).