Oral history is a field of study and a method of gathering, preserving, and interpreting the voices and memories of people, communities, and participants in past events. The teacher asks students to collect experiences of grandparents about the freedom struggle best illustrates the usage of oral history becausegenerally, grandparents tell many stories to the children to make them feel happy or to entertain them.in that stories when asked the grandparents may also tell their participation in the freedom struggles.this becomes a good source of oral history for the students.they may get inspired listening to the story of their grandparents struggling for freedom and country.this may remain in the minds of children for a long time under oral history.Hence teacher asking the students to collect experiences of grandparents about the freedom struggle best illustrates the usage of oral history. Additional InformationOn the other hand, all reminding three options are wrong because they are not correct sources for children to collect the oral history or the students could not collect the experience of specific groups in the society by just orally listing the names of famous freedom fighters.