Which configuration should be used to ensure mat AWS credentials (i.e ., Access Key ID/Secret Access Key combination) are not compromised?

A company is building software on AWS that requires access to various AWS services.

Which configuration should be used to ensure mat AWS credentials (i.e ., Access Key ID/Secret Access Key combination) are not compromised?
A . Enable Multi-Factor Authentication for your AWS root account.
B . Assign an lAM role to the Amazon EC2 instance.
C . Store the AWS Access Key ID/Secret Access Key combination in software comments.
D . Assign an lAM user to the Amazon EC2 Instance.

Answer: A

Explanation:

Reference: http://docs.aws.amazon.com/IAM/Iatest/UserGuide/IAMBestPractices.html