One of our clients wants to send a HTML mail containing a quiz.

I don't know how this sort of quiz is called in English, but i will try to explain:
There are questions in one ordered list, each question is followed by multiple possible answers. Each answer is associated with a letter. 
When you got the right answers, the associated letters will result the solution word.

**The problem:** 
Initially, the idea was to use a HTML form with input fields for the right answer(s).
**But** there is no chance to display HTML formular mail contents in mail clients like Outlook, HTML elements like inputs or textarea fields are not presentable as such. As far as i know, interaction using forms is impossible inside a HTML mail.

Also, there is no chance to display a link like 'show this mail in a browser'. This is technically not possible in this project, so the whole thing has to take place inside the mail client. Outlook will be used by most of the recipients.

What would you do in such case? 
Explain the mail recipient that he should write down the right letters to get the solution word? How would you work out such a quiz in a mail visually?