Resposta - Exibindo Mídias

Classe Media:

namespace exercise92.Models;

internal class Media
{
    public string Name { get; }

    public Media(string name)
    {
        Name = name;
    }

    public virtual void ShowDetails()
    {
        return;
    }
}

Classe Image:

namespace exercise92.Models;

internal class Image : Media
{
    public string Resolution { get; }

    public Image(string name, string resolution)
        : base(name)
    {
        Resolution = resolution;
    }

    public override void ShowDetails()
    {
        Console.WriteLine($"Image: {Name} - Resolution: {Resolution}");
    }
}

Classe Video:

namespace exercise92.Models;

internal class Video : Media
{
    public int Duration { get; }

    public Video(string name, int duration)
        : base(name)
    {
        Duration = duration;
    }

    public override void ShowDetails()
    {
        Console.WriteLine($"Video: {Name} - Duration: {Duration} minutes");
    }
}

Instâncias:

using exercise92.Models;

List<Media> digitalMedias = new List<Media>
{
    new Image("landscape.jpg", "1920x1080"),
    new Video("movie.mp4", 120)
};

foreach (Media media in digitalMedias)
{
    media.ShowDetails();
}