African lungfish, which are often found in small stagnant pools of fresh water, produce urea as a nitrogenous waste. What is the advantage of this adaptation? a. Urea takes less energy to synthesize than ammonia. b. Small stagnant pools do not provide enough water to dilute ammonia, which is toxic. c. Urea forms an insoluble precipitate. d. Urea makes lungfish tissue hypoosmotic to the pool.