我建议使用不同的数据结构来存储您的问题和答案：

var questions = [{
    question: "What color is the sky?",
    answers: ["Blue", "Red", "Pink", "Green"]
}, {
    question: "What color is grass?",
    answers: ["Green", "Yellow", "Purple", "Black"]
}, {
    question: "What color is dirt?",
    answers: ["Brown", "White", "Turqouise", "Gray"]
}];

在这种结构中，正确答案总是放在第一位。当实际显示选项时，您将首先对它们进行排序。这有两个优点：

• 您不必在数据结构中单独指出正确答案是什么
• 用户将以随机顺序获得选项，下次可能会有所不同

此外，您可能不需要实际提及问题编号，问题在整个数组中的位置定义了编号。
您的HTML还需要为答案添加标签：

<input type="radio" name="answer" value="" id="a1"><label for="a1"></label>
<input type="radio" name="answer" value="" id="a2"><label for="a2"></label>
<input type="radio" name="answer" value="" id="a3"><label for="a3"></label>
<input type="radio" name="answer" value="" id="a4"><label for="a4"></label>

这些标签的内容向用户显示答案。
下面是工作代码：
一个二个一个一个

你可以这样做.你有很多错误代码像引用不存在的数组

var cat1question1easy = ["1", "What color is the sky?", "Red", "Pink", "Blue", "Green", "Bluecorrect"];
cat1question1easy.name = "cat1question1easy";

var cat1question2easy = ["2", "What color is grass", "Yellow", "Purple", "Black", "Green", "Greencorrect"];
cat1question2easy.name = "cat1question2easy";

var cat1question3easy = ["3", "What color is dirt?", "Brown", "White", "Turqouise", "Gray", "Browncorrect"];
cat1question3easy.name = "cat1question3easy";

var cat1easyquestions = new Array(cat1question1easy, cat1question2easy, cat1question3easy);

循环数组以创建输入无线电

var randomcat1easyquestion = cat1easyquestions[Math.floor(Math.random() * cat1easyquestions.length)]
// create h3
var createH3 = document.createElement('h3');
createH3.textContent = randomcat1easyquestion[1]
// append it to dom element
document.getElementById('holder').appendChild(createH3);
// start looping from 2nd element as first two elemnts are not color
  for (var i = 2; i <= randomcat1easyquestion.length; i++) {
  var input = document.createElement('input');
  input.type = "radio"; // type of input
  input.name = "color"; // name is required for radio
  input.value = randomcat1easyquestion[i]; // assign value like red, blue, etc
  input.id = 'col_' + i;
  var label = document.createElement('label'); // label require for radi
  label.for = 'col_' + i;
  label.textContent = randomcat1easyquestion[i];
  document.getElementById('holder').appendChild(input);// append to dom
  document.getElementById('holder').appendChild(label) // append to dom
}

DEMO