The correct answer is option-1: Cryptocurrencies.

In recent years, cryptocurrencies have gained significant attention and popularity. They are digital or virtual currencies that use cryptography for secure transactions. Ethereum, Solana, Polkadot, and Tether are all examples of cryptocurrencies.

1. Ethereum: Ethereum is a decentralized, open-source blockchain platform that supports smart contracts. It allows developers to build and deploy decentralized applications (dApps) and run them without any interference or censorship.

2. Solana: Solana is another blockchain platform that aims to provide fast, secure, and scalable solutions for decentralized applications. It utilizes a unique consensus mechanism called Proof of History (PoH) to achieve high transaction throughput and low fees.

3. Polkadot: Polkadot is a multi-chain blockchain platform that enables different blockchains to connect and interoperate with each other. It offers a scalable and secure environment for building and deploying applications across multiple chains.

4. Tether: Tether is a type of cryptocurrency known as a stablecoin. Unlike other cryptocurrencies, its value is pegged to a traditional currency like the US Dollar or Euro. Tether is designed to provide stability and act as a digital equivalent of fiat currency in the crypto world.

Overall, these cryptocurrencies are mentioned in