You are starting to develop an application using AWS services. You are testing the authentication to the AWS services by querying them using REST API. Which of the following would be needed to make successful calls to AWS services using REST API?

Answer options:

A.User name and password
B.SSL certificates
C.Access Keys
D.X.509 certificates

Answer - C
The AWS Documentation mentions the following.
Access keys consist of an access key ID (for example, AKIAIOSFODNN7EXAMPLE) and a secret access key (for example, wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY). You use access keys to sign programmatic requests that you make to AWS if you use the AWS SDKs, REST, or Query API operations.
Option A is incorrect because it works with APIs or SDK. You need to use Access Key ID and Secret Access Key.
Options B and D are incorrect because SSL/TLS certificates or X.509 certificates are used to secure network communications. They are not used to access AWS resources.
For more information on Access Keys, please refer to the below URL-
https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html