Deserialize JSON object to List using GSON

I'm making a quiz game. I saved 10 questions in JSON file and need to add them to List. Here are two elements from JSON file:

{ 
  "1": {
    "question": "Q1",
    "options": [
      "O1",
      "O2",
      "O3",
      "O4"
    ],
    "answer": "O1"
  },
  "2": {
    "question": "Q2",
    "options": [
      "O1",
      "O2",
      "O3",
      "O4"
    ],
    "answer": "O2"
    },
}

and my Question class:

public class Question {
    private String question;
    private ArrayList<String> options;
    private String answer;
}

I know how to deserialize single JSONObject but have now idea how to add all question to one List in main class. Could you give me a hint?