Resposta - Certificado de Profissões

Classe Profession:

namespace exercise86.Models;

abstract class Profession
{
    public string Title { get; }

    public Profession(string title)
    {
        Title = title;
    }
}

Classe Analyst:

namespace exercise86.Models;

internal class Analyst : Profession
{
    public Analyst(string title) : base(title) { }
}

Classe Teacher:

namespace exercise86.Models;

internal class Teacher : Profession
{
    public Teacher(string title) : base(title) { }
}

Classe Certificate:

namespace exercise86.Models;

internal class Certificate
{
    public Profession Profession { get; }

    public Certificate(Profession profession)
    {
        Profession = profession;
    }

    public override string ToString()
    {
        return $"Certificate issued to: {Profession.Title}";
    }
}

Instâncias:

using exercise86.Models;

Analyst analista = new Analyst("Systems Analyst");
Teacher docente = new Teacher("Mathematics Teacher");
Certificate certificate1 = new Certificate(analista);
Certificate certificate2 = new Certificate(docente);

Console.WriteLine(certificate1);
Console.WriteLine(certificate2);