A financial services company is analyzing transaction data to detect fraudulent activities. They have two processing options: batch processing and stream processing. The company needs to decide which method to use based on the volume of transactions and the urgency of fraud detection. If they choose batch processing, they can analyze transactions every hour, but it introduces a delay in detecting fraud. Conversely, stream processing allows them to analyze transactions in real-time, but it requires more complex infrastructure and can be costlier. Given these considerations, which processing method would be more suitable for immediate fraud detection in a high-volume transaction environment?