2. What type of front ends
with a lot of precipitation,
like rain and snow:

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.

Ithink it's c selection but i don't really know. 

Sometimes but itt depends, their is a lot if drugs on campus too so you really can't just say that