The question requires exporting security event logs for a 2-year retention period while minimizing costs. Cloud Storage buckets (option B) are the optimal choice because they offer the lowest storage costs among the options, especially when using cost-effective storage classes like Coldline or Archive for long-term retention. The community discussion strongly supports this with 100% consensus on B, emphasizing cost optimization. While StackDriver logging (option C) can retain logs, it is more expensive for long-term storage. BigQuery datasets (option A) and Cloud Pub/Sub topics (option D) are not designed for cost-effective log archiving; BigQuery is optimized for analytics (higher costs), and Pub/Sub is for real-time messaging, not storage.