$elemmatch mongdb string array

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MongoDB.Bson;
using MongoDB.Driver;
using MongoDB.Driver.Builders;
using MongoDB.Driver.GridFS;
using MongoDB.Driver.Linq;
using MongoDB.Bson.Serialization;
using MongoDB.Bson.Serialization.Attributes;
using MongoDB.Bson.Serialization.IdGenerators;
using MongoDB.Bson.Serialization.Options;
using MongoDB.Bson.Serialization.Serializers;


namespace MongoDB
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                Console.WriteLine("Connecting to MongoDB...");

                var connectionString = "mongodb://localhost";
                var client = new MongoClient(connectionString);
                var server = client.GetServer();
                var database = server.GetDatabase("DbName");

                // get our