Which Statement Is FALSE in Reference to the Mammalian Synthesis

Which statement is FALSE in reference to the mammalian synthesis of urea?

A) Krebs was a major contributor to the elucidation of the pathway involved.
B) The amino acid arginine is the immediate precursor to urea.
C) The carbon atom of urea is derived from mitochondrial HCO₃^-.
D) The precursor to one of the nitrogens of urea is aspartate.
E) The process of urea production is an energy-yielding series of reactions.