dennis.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp1
{
    class Policy
    {
        public List<Unit> Units { get; set; }
    }

    class Unit
    {
        public string Type { get; set; }
        public List<Coverage> Coverages { get; set; }
    }

    class Coverage
    {
        public string CoverageCode { get; set; }
    }


    class Program
    {
        static void Main(string[] args)
        {
            var p = new Policy()
            {
                Units = new List<Unit>()
                {
                    new Unit()
                    {
                        Type = "OCx",
                        Coverages = new List<Coverage>()
                        {
                           new Coverage()
                           {
                               CoverageCode = "OCC"
                           }
                        }
                    }
                }
            };

            var policyCoverages = p.Units.SelectMany(u => u.Coverages.Select(c => new { Unit = u, Coverage = c })).ToList();

            if (!policyCoverages.Any(x => x.Unit.Type == "OC" && x.Coverage.CoverageCode == "OCC"))
            {
                Console.WriteLine("Policy must have at least one OC unit with an OCC coverage.");
            }
            else
            {
                Console.WriteLine("we are good");
            }


            Console.WriteLine("done");
            Console.ReadKey();
        }
    }
}