O prevent cross-contamination when preparing raw meat: A. Never combine different types of raw meat using the same cutting board B. Sanitize the cutting board after cutting raw meat and ready-to-eat foods C. Use a separate cutting board for raw meat and ready-to-eat foods D. Wash the raw meat before slicing it on the cutting board

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.