What is Hadoop?

a. an open source framework that allows for the distributed storage and processing of large datasets across clusters of computers using simple programming models.
b. does not follow the rules of Relational Database Management Systems
c. is designed to scale up from a single computer to thousands of clustered computers, with each machine offering local computation and storage.
d. can efficiently store and process large datasets ranging in size from gigabytes to petabytes of data.