A is proper https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_common-scenarios_third-party.html

By creating an IAM role and delegating access to the vendor's IAM role, you establish a trust relationship between accounts. This allows the vendor's automated tool to assume the role in the company's account and access the necessary resources. By attaching the appropriate IAM policies to the role, you can define the precise permissions that the vendor requires for their tool to perform its tasks. This ensures that the vendor has the necessary access without granting them direct IAM access to the company's account. B is incorrect because creating an IAM user with a password would require sharing the credentials with the vendor, which is not recommended for security reasons. C is incorrect because adding the vendor's IAM user to an IAM group in the company's account would not provide a direct and controlled way to delegate access to the vendor's tool. D is incorrect because creating a new identity provider for the vendor's AWS account would not provide a straightforward way to delegate access to the vendor's tool. Identity providers are typically used for federated access using external identity systems.

Create an IAM role in the company’s account to delegate access to the vendor’s IAM role. Attach the appropriate IAM policies to the role for the permissions that the vendor requires

Create an IAM role in the company’s account to delegate access to the vendor’s IAM role. Attach the appropriate IAM policies to the role for the permissions that the vendor requires

A. Create an IAM role in the company’s account to delegate access to the vendor’s IAM role. Attach the appropriate IAM policies to the role for the permissions that the vendor requires.

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Option A fulfill the requirements.

IAM role is the answer

A is correct answer.

https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_common-scenarios_third-party.html

https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-user_externalid.html

A is the correct answer.

My guess is D: https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_common-scenarios_third-party.html