Which factor increases speed of action potential propagation?
Go with C — Increased myelination. Within Action potential, that statement lines up with the standard definition and the usual exam wording you’ll see. In plain terms, Increased myelination is the option that correctly names the structure, process, or principle asked for in Action potential. Holding that picture in mind makes Increased myelination feel natural rather than something you only memorise. Link the term to a real body example (organ, tissue, or ion flow) so the idea stays concrete under exam pressure. A short mental diagram helps — start from stimulus or structure, follow the pathway, and stop at the functional result described by Increased myelination.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.