Concept:The theme-based approach in EVS organizes learning around broad topics to ensure complete coverage of all environmental concepts and issues.Explanation:Instead of teaching isolated facts, this approach groups related topics (like water, air, biodiversity, waste) into themes.Each theme covers multiple sub-topics, making sure students learn every important concept and issue within EVS.This structured method prevents missing any key area and gives students a well-rounded understanding of the subject.Answer:Option A. covering all concepts and issues