A peer-to-peer (P2P) system architecture is a network model where each node (peer) can act as both a client and a server, and communicate directly with other peers without relying on a centralized authority or intermediary. A P2P system architecture best supports anonymity for data transmission, by providing the following advantages:

It can hide the identity and location of the peers, by using encryption, pseudonyms, proxies, or onion routing techniques, such as Tor1 or I2P2. These techniques can prevent eavesdropping, tracking, or censorship by third parties, such as Internet service providers, governments, or hackers.

It can distribute the data across multiple peers, by using hashing, replication, or fragmentation techniques, such as BitTorrent3 or IPFS4. These techniques can reduce the risk of data loss, corruption, or tampering by malicious peers, and increase the availability and resilience of the data.

It can enable the peers to control their own data, by using consensus, validation, or incentive mechanisms, such as blockchain5 or smart contracts. These mechanisms can ensure the integrity and authenticity of the data transactions, and enforce the privacy policies and preferences of the data owners.