A group can belong to only one organization is the correct statement.

Groups are typically created and managed within a single organizational boundary and their ownership and configuration are tied to that organization. You can add members from other domains or organizations, and you can grant access across organizations, but that does not make the group belong to more than one organization.

A default access group can be deleted is incorrect because default or system created groups are often protected from deletion to preserve baseline access controls and settings.

A group can be suspended if it has no members is incorrect because suspension usually applies to user accounts rather than to group objects, and having no members does not generally trigger a suspend action for a group.

A group can belong to multiple organizations is incorrect because a group resource is owned by and scoped to a single organization even though its membership can include principals from other organizations.

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