Which of the following is used to allow or deny access to network resources?

Spoofing is an attack technique where a malicious actor forges source information (such as an IP address) to impersonate a trusted entity - it is not an access control mechanism.

An ACL (Access Control List) consists of ordered rules that match network traffic or resource requests against criteria such as IP address, port, or protocol, and then applies a permit or deny action. On network devices like routers and firewalls, ACLs are applied to interfaces to filter inbound or outbound traffic. They are the standard mechanism for enforcing access policy to network resources.

System hardening is the process of reducing a system's attack surface by disabling unnecessary services and applying patches, but it does not directly allow or deny access to specific network resources.

NFS (Network File System) is a distributed file sharing protocol that enables remote file access, but it is not itself a mechanism for allowing or denying access to network resources.