Final answer:
Flexibility is not a fundamental requirement for copyright protection, which is based on originality, fixation, and minimal creativity.
Step-by-step explanation:
The option that is not a fundamental requirement for something to be copyrighted is c) Flexibility. The fundamental requirements for a work to be copyrighted according to the laws of the United States include a) Originality, meaning the work must be independently created by a human author and not copied from another work; b) Fixation, which requires the work to be captured in a sufficiently permanent medium such that it can be perceived, reproduced, or communicated for more than a short time; and d) Minimal creativity, which calls for the work to possess at least some minimal degree of creativity. Since flexibility is not mentioned as a requirement in the legal framework that defines copyright eligibility, it is not a fundamental requirement for a work to be protected by copyright.