Practice question

Go with B — Cl⁻, urea and water. Within Excretory System, 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 Cl⁻, urea and water does in Excretory System. Holding that picture in mind makes Cl⁻, urea and water 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 Cl⁻, urea and water.