How to create multiple graded questions with player life count in Storyline?

OK. I thought about it a little more. Let's break down the problem into steps.

1. How to track player life?

I am thinking to create a number variable with a default value equal to 3. Every time player gets a question wrong, minus one. Since 10 questions are on 10 different slides, what is the scope of the variable in the storyline file? Does it work globally across all slides, or only in the slide where the variable is created? 

If Global Scope:

Trigger: Minus variable by 1 when the timeline starts on an incorrect layer in each question slide.

If Local Scope:

Then I need to move 10 questions into one slide. But can I still have multi-choice, multi-select, fill-in-blank questions?

2. How to show the retry slide when the variable is equal to 0?

To be continued...