interface Question
{
   ...
}

interface Questions
{
    int size();
    Question operator[](int index);
}

interface Repository
{
   //returns a random selection of up to total questions.
   Questions SelectRandomQuestions(int total);

   //returns a Question object that represents the question in the database.
   Question AddQuestion(Question newQuestion);

   //whatever other operations.
   ...
}

class SQLiteManager : Repository
{
   ...
}

main()
{
    var config = getConfigSomehow();

    var repository = new SQLiteManager(config.sqliteconfig);
    var quizManager = new QuizManager(repository);

    ...
}

class APIRepository : Repository
{
   ...
}

main()
{
    var config = getConfigSomehow();

    var repository = new APIRepository(config.apidetails);
    var quizManager = new QuizManager(repository);

    ...
}