Blockchain technology: Blockchain is a method of storing data in such a manner that it is difficult or impossible to alter, hack, or defraud it. A blockchain is a digital log of transactions that is copied and distributed throughout the blockchain's complete network of computer systems.
Three pillars of blockchain:
Decentralization: The actual definition of decentralization is the absence of a central authority. If we apply this notion to Blockchain, it indicates that the network is self-governing and does not have a central authority.
Transparency: In real life, transparency refers to anything that has no opacity. When we apply this notion to Blockchain, it means that there is no privacy. To be more specific, when it comes to transactions, all transactions are public and can be read by everyone on the network.
Immutability: Immutable implies precisely what it sounds like in real life: something that cannot be changed. When we talk about blockchain, we're referring to the fact that once a transaction is published into the system, it can't be changed.
Hence the correct answer is All of the Above.