How should the application use AWS credentials to acces…

You have an application running on an EC2 Instance which will allow users to download flies from a private S3
bucket using a pre-assigned URL. Before generating the URL the application should verify the existence of thefile in S3.
How should the application use AWS credentials to access the S3 bucket securely?

A.
Use the AWS account access Keys the application retrieves the credentials from the source code of the
application.

B.
Create a IAM user for the application with permissions that allow list access to the S3 bucket launch the
instance as the IAM user and retrieve the IAM user’s credentials from the EC2 instance user data.

C.
Create an IAM role for EC2 that allows list access to objects in the S3 bucket. Launch the instance with the
role, and retrieve the role’s credentials from the EC2 Instance metadata

D.
Create an IAM user for the application with permissions that allow list access to the S3 bucket. The
application retrieves the IAM user credentials from a temporary directory with permissions that allow read
access only to the application user.