Salam Alykom
Answer one of two questions? Is it possible in Moodle quiz?
Could you elaborate?
To add to what Marcus has said, yes, it is possible. However, your challenge could be with your grading criteria and the grade book, and how many of these answer one of two scenarios exist within the one quiz.
can you please tell me how to do it ?
It is not very difficult but it quickly becomes complicated.
The advantage of a user script is that you can adapt it to different cases (Adaptive mode or interactive mode with multiple tries. At the time of question selection, are students allowed to see the questions in detail or only a summary, can they change their choice, if so how many times, etc.) The downside is that you have to know a bit of JavaScript.
Ideally, a question type could be developed that would allow selection of the following questions. The downside is that such a question type would not be that easy to develop. I would be interested in doing it, but I don't have the time and maybe not the knowledge.
So I used a little user script that I wrote earlier. If you don't know JavaScript, I wouldn't recommend using it because you won't be able to adapt it to your specific needs. Plus, it's just a workaround that isn't perfect, written by someone with no real programming background. And, as Rick mentioned, you'll have to adjust the marks in the gradebook. Anyway, here's the link: https://moodleformulas.org/course/view.php?id=78§ion=52 ↗.
The advantage of a user script is that you can adapt it to different cases (Adaptive mode or interactive mode with multiple tries. At the time of question selection, are students allowed to see the questions in detail or only a summary, can they change their choice, if so how many times, etc.) The downside is that you have to know a bit of JavaScript.
Ideally, a question type could be developed that would allow selection of the following questions. The downside is that such a question type would not be that easy to develop. I would be interested in doing it, but I don't have the time and maybe not the knowledge.
So I used a little user script that I wrote earlier. If you don't know JavaScript, I wouldn't recommend using it because you won't be able to adapt it to your specific needs. Plus, it's just a workaround that isn't perfect, written by someone with no real programming background. And, as Rick mentioned, you'll have to adjust the marks in the gradebook. Anyway, here's the link: https://moodleformulas.org/course/view.php?id=78§ion=52 ↗.
Although the problem is not as complex as that of perpetual motion, I just realized that the solution I proposed does not work. The concept will have to be reviewed, but we will have to wait. 
What kind of question?