C # as a UI calling Prolog as an argument module

I need to write a program using C # as the UI and receive input. Then after that use Prolog to compute the answer and return C # for display. School project: D

Please advise how to do this, any free API I can use? I know C #, but it sucks about Prolog (which is what another team member does), so if I don't need to touch Prolog at all, this is preferable. Actually thanks for your help.