Detailed Explanation:

Answer: Option 4 — 1 and 3 only

Blockchain is a decentralized, distributed ledger technology where data is transparent and publicly inspectable, yet no single entity controls the network. While blockchain gained prominence through cryptocurrencies, its applications extend far beyond digital currencies to supply chain management, smart contracts, healthcare records, and more.

✅ Statement 1 – Correct: Blockchain functions as a public, distributed ledger that anyone can inspect, but which operates without centralized control, being maintained by a network of nodes.
❌ Statement 2 – Incorrect: Blockchain's architecture is not limited to cryptocurrency data; it can record and verify any type of digital information including contracts, identity records, supply chain data, and voting records.
✅ Statement 3 – Correct: The open-source and decentralized nature of blockchain allows developers to build applications (DApps) leveraging its core features—transparency, immutability, and decentralization—without requiring permission from any central authority.

📝 Short Notes: Blockchain Technology

• Definition: A distributed, decentralized ledger that records transactions across multiple computers in a way that makes records immutable and transparent.
• Key Features: Decentralization (no single point of control), Transparency (public inspection), Immutability (records cannot be altered retroactively), Security (cryptographic hashing).
• Structure: Data is stored in blocks, each containing transaction data, timestamp, and cryptographic hash of the previous block, forming a chain.
• Applications Beyond Cryptocurrency: Supply chain tracking, smart contracts, digital identity verification, healthcare records management, voting systems, land registry, and intellectual property protection.
• Types: Public blockchains (permissionless, like Bitcoin), Private blockchains (permissioned, restricted access), and Hybrid blockchains (combination of both).
• Consensus Mechanisms: Proof of Work (PoW), Proof of Stake (PoS), Practical Byzantine Fault Tolerance (PBFT), and others ensure network agreement on transaction validity.