Answer:
open-ended interview
Step-by-step explanation:
In an open ended interview, an interviewer is open to ask new question to the participants based on their responses in order to discover new interesting facts which can be useful for the study/research under which this interview is being conducted.
In a closed end interview a participant is a usually allowed to answer is one word either yes or no, true or false or some sort of rating inputs such as good , better , best etc.