There is a requirement for a vendor to have access to an S3 bucket in your account. The vendor already has an AWS account. How can you provide access to the vendor on this bucket.

Answer options:

A.Create a new IAM user and grant the relevant access to the vendor on that bucket.
B.Create a new IAM group and grant the relevant access to the vendor on that bucket.
C.Create a cross-account role for the vendor account and grant that role access to the S3 bucket.
D.Create an S3 bucket policy that allows the vendor to read from the bucket from their AWS account.

Answer – C
The AWS documentation mentions
You share resources in one account with users in a different account. By setting up cross-account access in this way, you don`t need to create individual IAM users in each account. In addition, users don`t have to sign out of one account and sign into another in order to access resources that are in different AWS accounts. After configuring the role, you see how to use the role from the AWS Management Console, the AWS CLI, and the API
For more information on Cross Account Roles Access, please refer to the below link:
http://docs.aws.amazon.com/IAM/latest/UserGuide/tutorial_cross-account-with-roles.html