China's Great Green Wall is the government's full-fledged attempt to intentionally increase forest cover through tree planting projects, but scientists have yet to determine its effectiveness. Choose 1 answer: (A) NO CHANGE (B) their (C) this (D) that

Scientists have conducted various studies to assess how effective this massive initiative has been. While it aims to combat desertification and improve air quality, challenges remain in terms of biodiversity and ecological balance that need ongoing research and attention. In addition, many grassroots organizations and local communities are getting involved in tree planting efforts beyond just government initiatives. Their contributions can provide vital insights and innovative methods that help enhance the overall success of the Great Green Wall project, creating a richer, more diverse environment.