Option A, To carry out the day-to-day activity of the government
I'll go over why the other options are wrong
Option B, The Supreme Court uses judicial review to determine constitutionality of laws. This is not the bureaucracy's job
Option C, I'm sure there is a bureau that assists other countries when disaster hits, but it's not a main day-to-day activity of the bureaucracy
Option D, this isn't the job of the bureau, although this is the way that bureaus hire people. In a way, this is sort of the spoils system.
If you have any questions, just ask! Good luck :))