Create a number n list dropdown TeacherN, populate its subquestions (e.g. Teachers)
Create an option groups for Classes , populate its subquestions (e.g. Classes)

Create a question Array (text), filter by Classes
Its subquestions are the codes of the classs {Class1_SQ001.question}
Its n subanswers are the Teachers codes in the form of {Teacher1.shown}

Execute the survey, complete one survey, export the answers in csv.

The field name of the Array text is "Associate Class and Teachers [{Class1_SQ001.question}]" instead of the value of the code
Field content of the column is {Teacher1.shown}, instead of the value of the code