JSON

JObject rss = JObject.Parse(jsonString);

var duoxianOject = (object)rss["questionObj"]["duoxuanList"];

IsoDateTimeConverter timeFormat = new IsoDateTimeConverter();
//将很乱的Json字符格式化
var DuoX = JsonConvert.SerializeObject(duoxianOject, Newtonsoft.Json.Formatting.Indented, timeFormat);

{
  "id": "137d2415703244f4ba8d222a9eaa7552",
  "title": "中国特色社会主义制度的基本制度包括",
  "score": 5,
  "sscore": 5,
  "type": "duoxuan",
  "teacherNote": "",
  "storeQuestionId": "ff808081719c15a00171a12d4f260310",
  "loreInfoId": "ff808081719c15cb0171a12cda753e28",
  "topicItemList": [
    {
      "isAnswer": "false",
      "index": "A",
      "content": "人民代表大会制度"
    },
    {
      "isAnswer": "true",
      "index": "B",
      "content": "中国领导下的多党合作和政治协商制度"
    },
    {
      "isAnswer": "true",
      "index": "C",
      "content": "民族区域自治制度"
    },
    {
      "isAnswer": "true",
      "index": "D",
      "content": "基层群众自治制度"
    }
  ],
  "sanswer": "B|C|D",
  "optionList": [
    {
      "isAnswer": false,
      "index": "A",
      "content": "人民代表大会制度",
      "indexName": "A",
      "title": "人民代表大会制度"
    },
    {
      "isAnswer": true,
      "index": "B",
      "content": "中国领导下的多党合作和政治协商制度",
      "indexName": "B",
      "title": "中国领导下的多党合作和政治协商制度"
    },
    {
      "isAnswer": true,
      "index": "C",
      "content": "民族区域自治制度",
      "indexName": "C",
      "title": "民族区域自治制度"
    },
    {
      "isAnswer": true,
      "index": "D",
      "content": "基层群众自治制度",
      "indexName": "D",
      "title": "基层群众自治制度"
    }
  ]
}

 public class TopicItemListItem
    {
        /// <summary>
        /// 
        /// </summary>
        public string isAnswer { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string index { get; set; }
        /// <summary>
        /// 人民代表大会制度
        /// </summary>
        public string content { get; set; }
    }

    public class OptionListItem
    {
        /// <summary>
        /// 
        /// </summary>
        public string isAnswer { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string index { get; set; }
        /// <summary>
        /// 人民代表大会制度
        /// </summary>
        public string content { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string indexName { get; set; }
        /// <summary>
        /// 人民代表大会制度
        /// </summary>
        public string title { get; set; }
    }

    public class AnswerMoudel
    {
        /// <summary>
        /// 
        /// </summary>
        public string id { get; set; }
        /// <summary>
        /// 中国特色社会主义制度的基本制度包括
        /// </summary>
        public string title { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public int score { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public int sscore { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string type { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string teacherNote { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string storeQuestionId { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string loreInfoId { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public List<TopicItemListItem> topicItemList { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string sanswer { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public List<OptionListItem> optionList { get; set; }
     }

//有很多JSON数据就用List    

<List<AnswerMoudel>> danxuan = JsonConvert.DeserializeObject<List<AnswerMoudel>>(DanX);

//单条

AnswerMoudel danxuan = JsonConvert.DeserializeObject<AnswerMoudel>(DanX);