______ are systems that provide external data sources to smart contracts.
Oracles
The Answer is option A. Oracles are data feeds from external systems that feed vital information into blockchains that smart contracts may need to execute under specific conditions. The growing need for oracles represents the continued expansion of blockchain systems into practical and real-world use cases, where accurate data is crucial. External data sources usually contain data that does not change very much or data that is too large to bring into the Active Data Cache.