Task: Question Answering
Input (English): Question: Which of the following factors does not influence the permeation of drugs through the stratum corneum ?: 
 Options:  <1> Degree of ionization of the drug. <2> Fixation to the tear fluid proteins. <3> Osmolarity of tears. <4> Instilled volume. <5> Ocular Pigmentation.
Output (English): 3