Task: Question Answering
Input (English): Question: Heating of 4-methoxy-3,5-dinitrobenzenesulfonic acid with dilute sulfuric acid gives: 
 Options:  <1> 4-Methoxy-3,5-dinitrophenol. <2> 3,5-Diamino-4-methoxybenzenesulfonic acid. <3> 4-methoxy-3,5-dinitrobenzenesulfonic acid anhydride <4> 2-Methoxy-1,3-dinitrobenzene. <5> An organic cation
Output (English): 4