Score and the Next Question

One question isn't much of a quiz. Now the player goes through all of them and collects points:

• Show the score in a paragraph with the class score, Score: 0 at the start. Each right answer adds a point.
• Once the player has answered, show a button Next question. It shows the next question with its answers, which can be clicked again, and without feedback.
• Above the question, show where the player is, Question 1 of 4, in a paragraph with the class progress.

The last question has no next one, so leave its Next question button out for now. The next exercise adds the end of the game.

A tip: which question is shown is a number in state: its index in questions, starting at 0, so the question is questions[index]. And the score can go up in the answer's handler, so it's right as soon as the feedback shows.