Correct about ectotherm and endotherm efficiency:
The keyed combination is A and C, yet the underlying assertions A–D are missing. In general, ectotherms spend relatively little assimilated energy maintaining a constant high body temperature and often show greater production efficiency than endotherms. Endotherms have high respiratory costs for thermoregulation, although assimilation efficiency also depends strongly on food quality and digestive physiology. These accepted principles support comparison of efficiencies, but they cannot establish which absent lettered statements correspond to them. Reliable inference requires the complete experi
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 17-19