Which of the following survey response methods is the most difficult for researchers to code for evaluation:

No options are given, but the most commonly used survey response methods are:

Multiple choice questions = generally easy to codeRating scale questions = also easy to code, since response scales have a finite number of choices, e.g. 2 true/false, 3 agree/disagree/undecided, 5 very bad/bad/fair/good/excellent Matrix questions. = are a little bit more complex since they involve several rating scale questions, but it is not something difficult eitherDropdown questions. = similar to multiple choice questionsOpen-ended questions. = this are hard to code since each subject can respond different things, e.g. the thing that I like the most about this project is bla, bla, bla. There are no pre-set answers given to the subjects. THIS TYPE IS THE MOST DIFFICULT TO CODE.Demographic questions = similar to multiple choiceRanking questions = similar to scaled questions