Task: Text Categorization
Input (English): Question: What is the purpose of the phthalyl group in phthalisulfatiazole ?: 
 Options:  <0> Improve intestinal absorption. <1> Prevent intestinal absorption. <2> Improve the passage through the blood-brain barrier. <3> Prevent passage through the blood-brain barrier. <4> Increase the affinity towards the therapeutic target of the drug.
Output (English): pharmacology