Correct Option: C

In the graph, the line a represents regulator, line b represents conformer and line c represents partial regulator. Organism that are able to maintain homeostasis by physiological means that ensures constant body temperature are called regulators. Organism that are not able to maintain a constant internal temperature are called conformers. Partial regulators are organisms that have the ability to regulate, but only over a limited range of environmental conditions, beyond which they simply conform.