Task: Question Answering
Input (English): Question: Which of the following membranes would be more fluid: 
 Options:  <1> Lipid bilayer with polyunsaturated fatty acids of 18 carbon atoms. <2> Lipid bilayer with saturated fatty acids of 18 carbon atoms. <3> Lipid bilayer with saturated fatty acids of 16 carbon atoms. <4> Lipid bilayer with polyunsaturated fatty acids of 16 carbon atoms. <5> All are equivalent in terms of fluency.
Output (English): 4