The answers provided by a respondent for a MSA question are checked against each answer box. This question type allows you to create a question such as, "Name 3 state capitals" and create 3 input boxes and 51 potential answers so that the user can enter any 3 answers in any answer box and receive full marks.
This question type differs from the Short Answer Question in that the short answer question supports multiple answer boxes, but requires distinct answer lists for each answer box.