The right answer is:

b) A blockchain is a distributed database that is duplicated across a peer-to-peer network of computers
b) If there is a change in the genesis block then all the subsequent blocks change accordingly
a) A blockchain have this charactristics: Immutability of the data, Cryptographically sealed, transparency

See here to know more about blockchain: https://steemit.com/blockchain/@hvonsteemit/3-knowledge-pills-on-blockchain

There is NO correct answer.

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