There is no efficacious remedy to unemployment problem in a country which has no ideological convictions.

Answer: Option C

Suitable : right or appropriate for a particular person, purpose, or situation.
Possible : able to be done or achieved.
Effective : successful in producing a desired or intended result.
Proper : denoting something that is truly what it is said or regarded to be; genuine.
Efficacious : (of something inanimate or abstract) successful in producing a desired or intended result; effective.

Synonym of Efficacious is Effective