Robert was a teacher in the Phoenix Union High School district for 10 years. At the age of 32, he decided to join the U. S. Regular Army, and was sent overseas. He could not teach and be in the Army at the same time. Robert's choice illustrates which of the following concepts?

Ifound the exercise on the internet. attached is the list mentioned above.in order for a compound to be considered optically active it can't have any axis or plan of symmetry. the molecule  shouldn't also  be superimposable on its mirror image.with such considerations, the compounds that are optically active are: -third compound on the first image is optically active; -second and third compound from the second image are optically actives.