How to create/update a multiple options field in custom fields

[antoinebidault]

I have a custom field in pipedrive set up as following :

How to create this kind of multiple options field using the client, there is no CustomField class which looks like an array of options ?

    var customFields = new Dictionary<string, ICustomField>();

   var optins = new List<string>()
    {
        "Newsletter",
        "Communication"
    };
    customFields.Add("Optins", <how to put the optins array here ?>);

    await _client.Person.Create(new NewPerson("Test")
    {
        Email = new List<Email>() { new Email() { Label = "Professional", Value = "test@github.com" } },
        CustomFields = customFields
    });