You are working on a project named amazon-ace, and want to list all the roles assigned to users in the project. Which of the following gcloud command would you use?

The `gcloud iam list` command is not a valid or standard `gcloud` command for listing IAM policies on a project.

The `gcloud projects list` command lists projects themselves, not the IAM policies or roles assigned within a specific project.

The `gcloud projects get-iam-policy` command is designed to retrieve the IAM policy for a specified Google Cloud project, which includes all the roles assigned to users and service accounts within that project. By providing the project name `amazon-ace`, this command will output the complete IAM bindings for the project, showing who has what roles.

The `gcloud iam get-iam-policy` command is used to get IAM policies for resources other than projects, such as a service account or a specific resource, not directly for a project itself with this syntax; `gcloud projects get-iam-policy` is the correct project-specific command.