A company has two VPCs in the us-west-2 Region in the same AWS account. The company needs to allow network traffic between them. Approximately 500 GB of data will transfer between the VPCs each month. What is the MOST cost-effective solution to connect these VPCs?

VPC peering is the most cost-effective solution for connecting two VPCs within the same AWS account and region, especially for moderate data transfer volumes like 500 GB/month. It uses AWS's internal network, providing high bandwidth and low latency without additional hardware or complex configurations. Data transfer costs over VPC peering are significantly lower than other options. AWS Transit Gateway is more suitable for connecting a larger number of VPCs (many-to-many connectivity) or connecting VPCs across different regions, making it overkill and more expensive for just two VPCs in the same region. AWS Site-to-Site VPN is primarily for connecting on-premises networks to AWS VPCs securely over the public internet, or for encrypted traffic between VPCs, and incurs higher data transfer costs and overhead. AWS Direct Connect provides a dedicated private connection from on-premises to AWS, which is not applicable here as both VPCs are already in AWS.