Voici une solution.
Il faut modifier la définition de la commande `\answer` pour quelle puisse collecter les différentes réponses.
!TEX none
\newcommand*\answer[1]{%
\xdef\multichoicehook{\ifx\multichoicehook\empty\else\multichoicehook, \fi\noexpand{\Alph{task}}}
\XSIMexpandcode{%
\SetExerciseProperty{solution-body}{\multichoicehook}}%
#1}
Il faut aussi ajouter le réglage suivant pour réinitialiser la commande `\multichoicehook`:
!TEX none
\xsimsetup{
exercise/template = item ,
solution/template = space ,
exercise/name = Q. ,
exercise/the-counter = \arabic{exercise}. ,
exercise/collect ,
random/sort = false,
exercise/begin-hook ={\let\multichoicehook\empty}
}
**ECM**.
\documentclass[12pt,a4paper]{article}
\usepackage{xsim}
\usepackage{tasks}
\NewTasksEnvironment[
label = \textbf{\Alph*.},
label-width = 15pt
]{choice}[\choice](4)
\DeclareExerciseEnvironmentTemplate{item}
{\description\item[\GetExerciseName~\GetExerciseProperty{counter}]}
{\enddescription}
\DeclareExerciseEnvironmentTemplate{space}
{\textbf{\GetExerciseProperty{counter}} }
{\quad}
\newcommand*\answer[1]{%
\xdef\multichoicehook{\ifx\multichoicehook\empty\else\multichoicehook, \fi\noexpand{\Alph{task}}}
\XSIMexpandcode{%
\SetExerciseProperty{solution-body}{\multichoicehook}}%
#1}
\DeclareExerciseCollection{Section1}
\xsimsetup{
exercise/template = item ,
solution/template = space ,
exercise/name = Q. ,
exercise/the-counter = \arabic{exercise}. ,
exercise/collect ,
random/sort = false,
exercise/begin-hook ={\let\multichoicehook\empty}
}
\begin{document}
\section{Section 1}
\collectexercises{Section1}
Il y a 2 réponses vraies par question, mais c'est toujours la dernière qui est reprise dans la liste des réponses!
\begin{exercise}
Lesquels donnent un résultat égale à $-6$?
\begin{choice}(2)
\choice \answer $-6 \times 1$
\choice $-3 \times -2$
\choice $-6 \times -1$
\choice \answer $3 \times -2$
\end{choice}
% Here the only fourth choice's answer key (the second correct one here "D") is diplayed in answers section
\end{exercise}
\begin{exercise}
Lesquels sont des pays africains?
\begin{choice}(4)
\choice \answer Nigeria
\choice \answer South africa
\choice Canada
\choice Germany
\end{choice}
% Here the only second choice's answer key (the second correct one here "B") is diplayed in answers section
\end{exercise}
\begin{exercise}
Lesquels sont exacts?
\begin{choice}(2)
\choice \answer $-2\times-3=6$
\choice $-2-3=-6$
\choice \answer $2+3=5$
\choice $-2+3=-5$
\end{choice}
% Here the only tirth choice's answer key (the second correct one here "C") is diplayed in answers section
\end{exercise}
\collectexercisesstop{Section1}
\subsection{Questions}
\printrandomexercises[collection=Section1]{5}
\subsection{Réponses}
\printsolutions[headings=false]
\end{document}
