Practice question

Go with B — Rapid muscle contractions. Within Thermoregulation, that statement lines up with the standard definition and the usual exam wording you’ll see. In plain terms, the functional job described in the stem is exactly what Rapid muscle contractions does in Thermoregulation. Holding that picture in mind makes Rapid muscle contractions 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 Rapid muscle contractions.