One argument against a multi-party system is the
encouragement of opposition and instability
banning of interest groups
inability to attract foreign assistance
high cost of conducting elections.
Correct answer is D
One argument against a mult-party system is the high cost of conducting election. It is very expensive in both men and materials.
It should be noted that encouragement of opposition and instability is also correct. The unhealthy rivalry, frequent political re-alignment and coalition make government of a country to be weak and unstable.