In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Q: Question: The interaction between the urea cycle and the citric acid cycle is carried out at the level of:
Options: <1> Uric acid. <2> Succinate <3> Ammonia. <4> Urea. <5> Fumarate
A:
5