The correct answer is option 3 - peer to peer digital currency. Bitcoin is a type of digital currency that operates on a peer-to-peer network. It is not controlled by any central authority, such as a government or bank. Bitcoin transactions are verified by network nodes through cryptography and recorded on a public ledger called blockchain.

Bitcoin has gained significant attention in the media due to its decentralized nature and potential for financial innovation. It is often portrayed as a form of digital currency that allows individuals to make secure transactions without the need for intermediaries.

Option 1, hologram stickers, is not related to bitcoin. Hologram stickers are used for authentication and anti-counterfeiting purposes.

Option 2, technology for improving the security features of paper currency, is also not related to bitcoin. While bitcoin does offer a secure method of digital transactions, it does not pertain to improving the security features of physical paper currency.

Option 4, Near Field Communication (NFC) technology, is unrelated to bitcoin. NFC is a form of wireless communication used for contactless payments and data exchange between devices in close proximity.

Overall, bitcoin is primarily associated with being a peer-to-peer digital currency.