4. Which of these choices best describes what a ratio shows?
in
A. a comparison between two quantities
B. family relationships over several generations
C. the alleles of parents and offspring for a
of
given trait
D. the likelihood or chance that something will
happen

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.