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: Indicate which of the following is a mitochondrial disease: 
 Options:  <1> α-thalassemia <2> Essential fructosuria. <3> Leigh syndrome. <4> Cushing's syndrome. <5> Sickle cell anemia
