The question asks for a cost-effective backup and restore solution for migrating an Oracle-based application to Google Cloud, with specific RTO and RPO requirements. Option A suggests using on-premises tapes for backups, which does not leverage Google Cloud's capabilities and may not meet the RTO and RPO requirements effectively. Option B proposes using Actifio with Cloud Storage's Nearline Storage class, which is cost-effective for backups but Nearline Storage has retrieval times that may not meet the 15-minute RPO. Option C recommends backing up directly to Cloud Storage's Standard Storage class, which offers fast access times suitable for the 2-hour RTO and 15-minute RPO, and is cost-effective for frequent access. Option D suggests migrating to Compute Engine but still relying on on-premises tapes, which is not a cloud-native solution and may not meet the performance requirements. Therefore, the best option is C, as it directly addresses the need for a cost-effective, cloud-native solution that meets the specified RTO and RPO.