The correct answer is C because Google recommends using groups for permission assignments to streamline management and adhere to best practices. This approach simplifies permission management as team changes (additions or removals) only require updates to the group membership, not the IAM policies.

• Option A is incorrect because assigning permissions individually to users is less efficient and harder to manage than using groups.
• Option B and D are incorrect because the gcloud iam roles create command is used for creating custom roles, not for assigning existing roles to users or groups.