Please can someobody help with the 3D structures drawn as optical isomers (not skeletal formula)

An amine can be formed when 2-iodopentane is heated with ammonia in a sealed tube. This is an example of a nucleophilic substitution reaction. i) Draw the 3D structures of the two isomers of the amine product that you named and produced a drawing of in part a ii). ii) With reference to a different named example, explain the term 'optical isomer'. You should draw the 3D structure of the example considered