Task: Text Categorization
Input (English): Question: What two non-protein amino acids participate in the urea cycle ?: 
 Options:  <0> Proline and hydroxyproline. <1> Ornithine and citrulline. <2> Alanine and arginine. <3> Oxalacetate and malate. <4> Serine and GABA.
Output (English): pharmacology