Which of these statements about the relative toxicity, water costs, and energy costs of the different nitrogenous waste removal methods (direct ammonia release or conversion into urea or uric acid) is NOT true?

A. Conversion into urea requires the most water
B. The toxicity level of urea is intermediate between that of ammonia and uric acid
C. Ammonia is the most toxic
D. Conversion into uric acid requires the most energy