how to randomize constant in javascript and display a javascript quizz results [closed]

I am doing this exercise to learn more about JS.

i have 3 questions:

1. at the end of quizz how to display wrong answered questions and hihglight selected option with one color and correct one with another
2. how to display the questions with theier answers in random order
3. if i have more than 15 questions added, i want to disaply only random 10 of them

this is my source https://www.sitepoint.com/simple-javascript-quiz/