Task: Question Answering
Input (English): Question: The forces that stabilize the alpha helix are: 
 Options:  <1> Intra-chain hydrogen bridges parallel to the axis of the helix. <2> Disulfide bridges between methionines. <3> Hydrogen bridges between chains perpendicular to the axis of the helix. <4> Van der Waals forces among the radicals. <5> Links between lysine radicals.
Output (English): 1