Task: Question Answering
Input (English): Question: The enantiomers of a molecule are: 
 Options:  <1> Very different in all its chemical and physical properties. <2> Superimposed mirror images. <3> Distinguishable by their optical activity. <4> The result of the cyclization of a molecule in different positions. <5> Interconvertible without rupture of covalent bonds.
Output (English): 3