Ipcc costing and fm theory

I am appearing for ipcc in NOV 2014. In costing and fm, total 32 marks theory comes in exam i.e. two 16 marks question. My question is that whether to attempt both theory questions or leave 1 question. i have heard that 90% of theory comes from practice manual only and one can score minimum 25 out of theory of 32 marks by doing only practice manual. So i was confused which one to choose from below options:

OPTION 1 - Study every chapter theory from practice manual and attempt both theory questions. 

OPTION 2 - Study only main chapters from which theory will definately come and attempt only 1 question of theory.

PLease Suggest best alternative...THANK YOU