You have an EC2 Instance in development that interacts with the Simple Storage Service. The EC2 Instance is going to be promoted to the production environment. Which of the following features should be used to grant the EC2 instance suitable permissions to access the Simple Storage Service?

Answer options:

A.IAM Users
B.IAM Roles
C.IAM Groups
D.IAM policies

Answer - B
The AWS Documentation mentions the following.
An IAM role is similar to a user, in that it is an AWS identity with permission policies that determine what the identity can and cannot do in AWS. However, instead of being uniquely associated with one person, a role is intended to be assumable by anyone who needs it. Also, a role does not have standard long-term credentials (password or access keys) associated with it. Instead, if a user assumes a role, temporary security credentials are created dynamically and provided to the user.
For more information on IAM Roles, please refer to the below URL:
https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html