CommonLit only allows you to create an assignment for a given text once in each class. Therefore, you cannot create one assignment in the same class for a text with only the multiple-choice assessment questions selected from the Assessment Options dropdown, and then create another assignment for the same text with only the short answer assessment questions selected.
If you create an assignment and selected the wrong choice from the Assessment Options dropdown, you can delete the assignment and then recreate it. If you already have student data and do not want to delete the assignment, you can choose to create a second version of the assignment with different Assessment Options from your Individual/Small-Group Assignments page. However, please note that assignments from this page are not included in Student Performance or Class Performance data.