Which of the Following Sequence of Events Best Explains the Formation

Multiple Choice

Which of the following sequence of events best explains the formation of carbamate in the mechanism of carbamoyl phosphate synthetase?

A) Bicarbonate and ATP form carboxyphosphate, then NH₃ performs a nucleophilic attack on carboxyphosphate to form carbamate
B) Bicarbonate is attacked by NH₃ to produce carbamate with ATP hydrolysis occurring solely to drive the reaction to completion
C) Bicarbonate reacts with ATP forming carboxy adenylate and pyrophosphate, then NH₃ performs a nucleophilic attack on carboxy adenylate to form carbamate
D) NH₃ reacts with ATP, which then reacts with bicarbonate followed by loss of phosphate to produce carbamate
E) none of the above