A 25-year-old woman is hospitalized for evaluation of episodes in which she appears to lose consciousness, rocks her head from side to side, and moves her arms and legs in a non-synchronous, bicycling pattern. The episodes occur a few times per day and last 2 to 5 minutes. Electroencephalography During the episodes does not reveal any ictal activity. Immediately after a fit, her sensorium appears clear. What is most likely diagnosis? A. Epilepsy B. Malingering C. Somatic symptom disorder D. Conversion disorder, with attacks or seizures