Which statement best describes the supervised learning process in building a question-answering system?
A. The system ingests the corpus and is able to answer questions after ingestion
B. A human supervisor monitors the progress of the learning, evaluates the answers, and incrementally improves the results
C. The system learns by example from a set of questions and their respective answers
D. The system ingests a corpus and asks a human supervisor for clarification in natural language when it encounters a subject it does not understand