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: The selectivity in the nucleophilic opening that occurs in the substituted oxacyclopropanes is called: 
 Options:  <1> Enantioselectivity <2> Diastereoselectivity. <3> Regioselectivity <4> Mesoselectivity <5> None of them.
