A Company Uses Amazon S3 to Host a Web Application

A company uses Amazon S3 to host a web application. Currently, the company uses a continuous integration tool running on an Amazon EC2 instance that builds and deploys the application by uploading it to an S3 bucket. A Solutions Architect needs to enhance the security of the company's platform with the following requirements: A build process should be run in a separate account from the account hosting the web application. A build process should have minimal access in the account it operates in. Long-lived credentials should not be used. As a start, the Development team created two AWS accounts: one for the application named web account process; other is a named build account. Which solution should the Solutions Architect use to meet the security requirements?

A) In the build account, create a new IAM role, which can be assumed by Amazon EC2 only. Attach the role to the EC2 instance running the continuous integration process. Create an IAM policy to allow s3: PutObject calls on the S3 bucket in the web account. In the web account, create an S3 bucket policy attached to the S3 bucket that allows the build account to use s3:PutObject calls.
B) In the build account, create a new IAM role, which can be assumed by Amazon EC2 only. Attach the role to the EC2 instance running the continuous integration process. Create an IAM policy to allow s3: PutObject calls on the S3 bucket in the web account. In the web account, create an S3 bucket policy attached to the S3 bucket that allows the newly created IAM role to use s3:PutObject calls.
C) In the build account, create a new IAM user. Store the access key and secret access key in AWS Secrets Manager. Modify the continuous integration process to perform a lookup of the IAM user credentials from Secrets Manager. Create an IAM policy to allow s3: PutObject calls on the S3 bucket in the web account, and attack it to the user. In the web account, create an S3 bucket policy attached to the S3 bucket that allows the newly created IAM user to use s3:PutObject calls.
D) In the build account, modify the continuous integration process to perform a lookup of the IAM user credentials from AWS Secrets Manager. In the web account, create a new IAM user. Store the access key and secret access key in Secrets Manager. Attach the PowerUserAccess IAM policy to the IAM user.