Identify the nitrogenous excretory waste based on the following features. 

a.   Requires a large amount of water for its elimination.

b.   Readily soluble and is generally excreted by diffusion across body surfaces.

c.   Generally excreted through gill surfaces in fish. 

d.   In fishes, kidneys do not play any significant role in its removal.

• A

  Ammonia

• B

  Urea

• C

  Uric acid

• D

  Creatinine