Which of the following statements regarding the features of blockchain technology are correct? 1. Records stored in the database may be made visible to relevant stakeholders without risk of alteration. 2. Copies of the entire database are stored on multiple computers on a network, syncing within seconds. 3. Consortium blockchain is a blend of public and private blockchains allowing selective data access. 4. Mathematical algorithms make it impossible to change or delete any data once recorded and accepted.

Blockchain technology is a distributed ledger system where records are stored across a network of computers. Statement 1 is correct as blockchain allows transparent records visible to relevant stakeholders while being tamper-resistant due to cryptographic hashing. Statement 2 is correct because blockchain works on a distributed ledger principle where copies of the database are maintained across multiple nodes and synchronized within seconds. Statement 4 is correct as mathematical algorithms (cryptographic hashing) make data alteration practically impossible once recorded and accepted in blocks. Statement 3 is incorrect because a consortium blockchain is a permissioned blockchain governed by a group of organizations, not a blend of public and private blockchains (that description more closely fits hybrid blockchain). Hence options 1, 2, and 4 are correct.