Which statements accurately describe why the body converts NH₄⁺ to urea? (Select all that apply)
I. Urea is less toxic than NH₄⁺ and can be safely excreted in urine.
II. NH₄⁺ is readily eliminated from the body without conversion.
III. The conversion of NH₄⁺ to urea helps in maintaining the body's acid-base balance.
IV. Urea formation allows the body to excrete excess nitrogen while conserving water.

• A. I and III
• B. I and II
• C. I, III, and IV
• D. I, II, III, and IV

Answer: (C)