The correct options are
A Unitary system - Administrative delay
B Federal system - Checks despotism of centre
C Federal system - Rigid Constitution
Unitary system of government is less expensive and suitable for smaller countries. Their disadvantages include difficulty in meeting local needs in bigger countries, administrative delay and making its way for despotism. Merits of the Federal system include the creation of a balance between local autonomy and central power, checking despotism of centre, administrative efficiency, economic and cultural progress. The Federal systems will have a weaker centre. It can also lead to conflict between centre and state.