Jeb studies the motivation of young environmentalists. He wants to understand more about the ways in which these children think about environmental issues and how their ideas have developed. He identifies participants through a local "green kids" group and goes to their next meeting. He selects several of the children through convenience and asks them open-ended questions that he has written down in advance. He records their responses as they answer the questions. Jeb is best displaying which of the following types of interviews?

Structured and formal

Unstructured and formal

Structured and informal

Unstructured and informal