You will be given a definition of a task first, then some input of the task.
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'.

Question: Synovial fluid from patients with gout often contains: 
 Options:  <1> Hippuric acid crystals. <2> Tyrosine crystals. <3> Triple phosphate crystals. <4> Urate crystals. <5> Calcium oxalate crystals.
Output:
4