Answer: The correct answer is- E) structural framework.
Fibrous proteins are water insoluble, elongated filamentous like structures that that provide structural framework ( they have special types of helices in their structures) to the cells or tissues of organisms.
They contain repetitive amino acid sequences in their structure that provides strength to the structure.
They are very less sensitive to any change in pH, temperature, as well as enzymatic digestion.
They are usually involved in the formation of connective tissue.
Example of fibrous protein- Actin, myosin, elastin, keratin.