In which consensus mechanism do validators apply received transactions without any consensus?

The choice indicating "Solo" as the consensus mechanism where validators apply received transactions without any consensus is correct because, in this mechanism, there is no need for multiple parties to reach an agreement before transactions are processed. Solo validation means that a single node operates independently and validates transactions on its own, making it more straightforward but potentially less secure and resilient compared to consensus mechanisms that require a wider agreement.

In Solo, the validator acts autonomously, processing the transactions based solely on its own criteria and state, which allows for quick transaction execution since there are no conflicting inputs or the need for agreement among multiple validators. This contrasts with other mechanisms, such as Proof of Stake or PBFT, where a consensus must be reached among multiple validators, introducing additional layers of complexity and security but also potentially slowing down transaction processing.