You are answering a USMLE-style medical question. Question: In order to assess the feasibility and evaluate the outcomes of cerclage wiring as a supportive approach to osteosynthesis in femur fractures, a group of orthopedic surgeons studied 14 patients with primary and periprosthetic fractures of the thigh bone. Parameters such as patient demographic, type of implant, number of wires used, fracture union rate, and potential complications were thoroughly recorded and analyzed in all the patients, with a mean duration of patient follow-up of 16 months. Union was achieved in all patients with a mean duration of 90 days, and there were no complications found in patients included in the study. The authors were satisfied with their findings and, due to the prospective nature of their research, submitted their study to a journal as a cohort study (which they noted in the study title as well). However, the journal editor returned the article, suggesting that it should be submitted as a case series instead. The editor made this suggestion to the authors for which of the following reasons? Options: A) No prevalence assessment B) Low number of patients C) Ascertainment bias D) Lack of risk calculation Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.