While viewing packet capture data, you notice that one IP is sending and receiving traffic for multiple devices by modifying the IP header, Which option is making this behavior possible?

TOR (The Onion Router) anonymizes traffic by routing it through multiple relays, but it does not modify IP headers to multiplex multiple devices behind a single address.

NAT operates at the network layer and rewrites the source or destination IP addresses in packet headers, allowing one external IP address to serve as the public-facing address for many internal devices on a private network. This is exactly the behavior described - one IP appearing to send and receive traffic on behalf of multiple devices by modifying the IP header.

Encapsulation wraps a protocol or data inside another protocol's frame or packet, but it does not modify the original IP header to allow one IP to represent multiple hosts.

Tunneling encapsulates one network protocol within another for transport, but does not perform address translation to map multiple internal devices to a single external IP.