How to limit the choice of performers in Redmine?

Question

Redmine

In the problem book, there are many projects and many tasks. The question needs to be made possible (rights) for a certain group of people so that they can choose ONLY one performer (it doesn’t matter how many people have access to the problem book). That is, like this: he
writes the answer, and he has only ONE performer by default.
OR
to the author of the issue