Need my function to work with different lists of different values (classes)

Hi. I am currently making a board-style educational game. In my game there are 3 different types of card (Calculations, Math Riddles and Math Problems). I have 3 sub-classes for each card type which all inherit from a Card base class. Then I saved all my cards in three different lists

The problem is that I wrote a function that needs to access each list of the cards, but as I have three different list of different types, I can’t put the into an array of lists and use and index.

In the function I replace some asterisks in a string with numbers from an array.

After investigating I only have found 2 options
1: I copy and paste the exact function and change the list
2: I found something about making arrays of objects which can contain things from any type but they seem not very efficient

Any ideas? I want to make it as good as possible and I think there must be a better way, thank you for your time

  //This is when I declare the tree different lists
 public List<CalculationCard> CalculationCards = new List<CalculationCard>();
    public List<RiddleCard> RiddleCards = new List<RiddleCard>();
    public List<EnigmaCard> EnigmaCards = new List<EnigmaCard>();

    private string DisplayTask(int index, int dif) //Function I mentioned

        string task = database.EnigmaCards[index].task;
        bool asteriscLeft = true;
        int count = 0, i;

        while (asteriscLeft)
            i = task.IndexOf("*", 0); //Search the next asterisk

            if (i != -1)
                string n = database.EnigmaCards[0].numbers[dif][count]; //This enigmaCards is the list that I need to change
                task = task.Remove(i, 1).Insert(i, n); //Replaces the asterisk with the correct number
                asteriscLeft = false;

        return task;

So if I understand correctly: CalculationCard, RiddleCard, and EnigmaCard all inherit from a Card class?

If so you can use List<Card> or Card[]. For Googling purposes, this is called polymorphism.