The correct solution to meet the requirements of connecting securely to the Amazon S3 buckets over a private connection from Amazon EC2 instances with no additional cost is Option C: Create one gateway VPC endpoint for all the S3 buckets. Add the gateway VPC endpoint to the VPC route table.
Explanation:
A gateway VPC endpoint allows you to connect to Amazon S3 from your VPC without requiring an internet gateway, NAT gateway, or VPN connection. It provides a private connection to Amazon S3 over your Amazon VPC using Amazon's private network.
Since the company wants to connect to 50 Amazon S3 buckets securely over a private connection from its Amazon EC2 instances in the same AWS Region, creating one gateway VPC endpoint for all the S3 buckets is the most efficient and cost-effective solution.
By creating one gateway VPC endpoint, you can connect to all S3 buckets in the same Region without the need to create multiple VPC endpoints for each bucket, thus reducing complexity and avoiding additional costs