The area or the land where a large number of waste materials are buried in the soil is called landfills.Example: Sanitary landfills, Municipality wastes landfills, etc. These types of activities help students to explore their own world and enjoy their surroundings.These types of activities generate curiosity to learn or think about the situation and they think divergently by covering all the aspects to mitigate the problem.Visits are necessary for a student's curriculum which helps the student to know our surroundings.So by all these references, we can conclude that (c) and (d) are correct.?Important PointsStudents can find causes of the landfills, such as:Uses of plastics, etc.Students can find the effect of the landfills, such as:Heath problems, etc.But it is not possible all the time that students can analyze the situation and find out the way to mitigate the problem.That's why option(4) is not considered.Additional Information Effects of landfills are:Water supply contamination.Increase soil pollution, air pollution, and water pollution.Increase the level of CO2 .Negative impact on health.