Task: Question Answering
Input (English): Question: The treatment of 1-hexyne with 1 mole of hydrogen bromide results in: 
 Options:  <1> 1-bromo-1-hexene. <2> 1-bromo-2-hexene. <3> 1-bromo-3-hexene. <4> 2-bromo-1-hexene. <5> 2-bromo-2-hexene.
Output (English): 4