Linux is an example of___?

What is the foundation for proper monitoring, load balancing and routing in distributed systems

Worth 50 points answer them bc i am not sure if i am wrong

The best definition of an idiom is a. a word or phrase that describes a noun b. a word or phrase describing a verb c. a phrase containing figurative language in which the word expresses a different idea from its exact meaning d. a phrase that compares two unlike objects or ideas