Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: 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.
