I am assuming that you have one option available to each student and that you have limited each option to only one student to make it close as soon as it is chosen. Make two groups: Section A and Section B. Now make a grouping for called Separate Section Groups and put both your groups into that grouping. This will protect you later in the course when you want to add more groups. Make sure that in the Common Module Settings in the choice edit page, you chose "separate groups", and the Grouping "Separate Section Groups". When students in the different sections, they will see the choices that only their section members have selected and not the other section's members choices. You as an instructor can filter them by group as the attached picture shows the drop down window in the upper left corner under separate groups.
If any of the assumptions are incorrect, then let us know.