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: In smooth muscle fibers: 
 Options:  <1> The functional unit is the sarcomere. <2> The contraction is regulated by troponin. <3> The autonomous system always innervates all fibers. <4> Actinamyosin cross bridges do not form. <5> There may be hormone receptors.
