to compile option A is correct OK, then you need to run ...
now your question is why option D is incorrect.
from oracle documents:
The default class path is the current directory. Setting the CLASSPATH variable or using the -classpath command-line option overrides that default, so if you want to include the current directory in the search path, you must include "." in the new settings.
I strongly suggest you to compile as in option A then analyze the output ;)
For more detail:
classpath