Millionaire Mode

Which of the following options is the best substitute for the underlined words in statement III?

Directions: In this passage, errors or parts of a sentence, which have been left out, have been underlined. To correct these errors and correctly complete the passage, choose the correct option.
Statement I: It was home-science class today. The new students of Grade 3 had waited                                    
Statement II: for Mrs. Sylvie, their home–science teacher, to arrive. As she walked, they                                   
Statement III: all stood up and wished her good morning. Mrs. Sylvie told the principal that the topic                     
Statement IV: of discussion of the day was "Home.” A house is called a home _________