It can be inferred from the last paragraph that______.A．planting trees can be very helpful

It can be inferred from the last paragraph that______.

A．planting trees can be very helpful for a country"s economy

B．most land in Iceland belongs to private landowners

C．there is still very few trees in Iceland at present

D．the last two decades witnessed the great effort in planting in Iceland

请帮忙给出正确答案和分析，谢谢！