assalm o alikum guys,

i am also thinking to take test in 2016 and choose following subjects

Forestry
Agriculture
Psychology
business administration
mercantile law

but i need some help, actually i am confused, whether i should choose business administration or public administration. can you guys help me about this problem & also i hope you have reviewed the syllabus so what about the selection of best books for the subject as i have gone through various threads & felt myself dizzy as every person has its own opinion about the books