AdaptiveCard

MainBot.cs

 // Reply to the activity we received with an activity.
 var reply = turnContext.Activity.CreateReply();

// combine path for cross platform support
string[] paths = { ".", "Resources", "adaptiveCard.json" };
var adaptiveCardJson = File.ReadAllText(Path.Combine(paths));

var adaptiveCardAttachment = new Attachment()
{
    ContentType = "application/vnd.microsoft.card.adaptive",
    Content = JsonConvert.DeserializeObject(adaptiveCardJson),
};

 reply.Attachments.Add(adaptiveCardAttachment);

 // Send the card(s) to the user as an attachment to the activity
 await turnContext.SendActivityAsync(reply, cancellationToken);