The correct answer is B. When dealing with HTTP status codes of 5xx (server errors) and 429 (too many requests), it is recommended to implement retry logic using a truncated exponential backoff strategy. This approach involves retrying the failed request after an initial delay, and then exponentially increasing the delay for each subsequent retry up to a maximum limit. This helps to alleviate temporary issues with the service or high request rates. Other options, such as using gRPC, ensuring multi-regional buckets, or monitoring service status, do not directly address the need for handling these specific types of errors in a robust manner.