The discussion method involves an open-ended, collaborative exchange of ideas between a teacher and the student or between students, to improve students thinking, learning, problem-solving, comprehension, or literary appreciation. Discussion is beneficial to learning because it allows students to process knowledge rather than merely accept it. The purpose of a discussion is to get students to think about the course material differently.Objectives of discussion on switching off the engine of vehicles while waiting-?To let children know about air and noise pollution caused by vehicles and their effect on people, wildlife, and plants.To let children know about the judicious use of nonrenewable resources (petrol, diesel), as they are limited in the nature and future they will be exhausted.To let children know about misuse of natural resources by unnecessary idling of cars, trucks, and buses as modern vehicles do not require warming, so there is no need to turn on the engine until you are ready to drive.To let children discuss the steps not being taken by the government to stop this issue.Hence, we conclude that the teacher wants to convey all the given options that are A, B, C, and D.