Option C is correct because checking the Identity and Access Management (IAM) roles assigned to the service account at the project or inherited from the folder or organization levels is the recommended way to verify the service account's permissions in the specific project. Option A is incorrect because querying audit logs to find permission-denied errors could be part of the troubleshooting process, but it doesn't directly validate the roles assigned to the service account in the project. Option B is incorrect because checking organization policies is not directly related to validating the service account's roles and permissions in the specific project. Option D is incorrect because running a query to determine which resources the service account can access might help with troubleshooting, but it doesn't directly address the permission issues in the given project.