According to the researchers, what is the average price tag of these fundamental ecosystem services?

According to the researchers, what is the average price tag of these

1.	According to the researchers, what is the average price tag of these fundamental ecosystem services?
A.	US $ 300 trillion a year
B.	US $ 33 trillion a year
C.	US $ 5 trillion a year
D.	US $ 1000 trillion a year
Answer» D. US $ 1000 trillion a year