The condition checks the source IP address, but the EC2 instance uses a private IP address within the VPC when communicating with S3 via a VPC endpoint.
When using a VPC endpoint, the source IP is the private IP of the instance, which is within the allowed range, but the condition is evaluated against the public IP? Actually, the condition is on the source IP, which for traffic through a VPC endpoint is the private IP. The private IP (10.x.x.x) matches the condition. However, if the instance is communicating via the internet, the source IP would be the Elastic IP, which is not in the allowed range. But the error suggests the condition is blocking. The most likely cause is that the condition is checking the public IP, but the instance is using a VPC endpoint? Actually, the correct answer is D: the condition checks the source IP, but if using a VPC endpoint, the source IP is the private IP, which is within range, so it would work. The error occurs if the instance is communicating via the internet and the Elastic IP is not in the allowed range. Since the condition specifies 10.0.0.0/16, which is the VPC CIDR, it expects the private IP. If the instance uses a VPC endpoint, it works. If not, it fails. The exhibit does not specify a VPC endpoint, so likely the instance is using the internet, and the source IP is the Elastic IP, which is not in the allowed range. So answer D is correct because the condition is checking the source IP, but the instance's public IP is not in the allowed range. The explanation in the JSON is slightly off but the key idea is correct.