Comprehensive and Detailed 250 to 300 words of Explanation (AWS documentation-based, no links):

To capture traffic metadata to and from network interfaces in a VPC, the correct telemetry source is VPC Flow Logs. Flow Logs can publish records to destinations such as CloudWatch Logs, which is a natural first landing zone for near-real-time log ingestion and centralized retention/permissions. The next requirement is to stream that data to Amazon OpenSearch Service for analysis with minimal operational overhead.

Amazon Data Firehose is purpose-built for fully managed delivery of streaming data to destinations including OpenSearch. Firehose handles buffering, batching, retry behavior, and optional transformations, and it minimizes the need to build and operate custom consumers. Therefore, sending VPC Flow Logs to CloudWatch Logs and then using Firehose to deliver to OpenSearch is an operationally efficient and scalable pattern.

Option A uses Kinesis Data Streams, which would require building/operating consumers (or additional integration components) to read from the stream and load into OpenSearch, adding operational complexity compared with Firehose’s managed delivery. Options C and D are incorrect because CloudTrail records API activity and governance events, not VPC network flow records; VPC Flow Logs do not publish to CloudTrail trails.

Thus, B best meets the requirement: Flow Logs capture the network interface traffic metadata; CloudWatch Logs provides near-real-time log collection; and Firehose provides managed streaming delivery into OpenSearch for indexing and analytics with minimal operational effort.