Reptiles, by drawing their body heat directly from the Sun rather than burning calories to generate it, can survive on ten percent of the nourishment that a mammal of similar size would normally require

• Arather than burning calories to generate it  
• Brather than the generation of body heat by burning calories  
• Cand not from generating it by burning calories  
• Dinstead of by burning calories for generating it  
• Einstead of body heat generated by burning calories