What is scientists' attitude towards the future of Chad Lake

A．To learn whether trees can still absorb carbon dioxide under extreme conditions.
B．To get more oxygen from these trees.
C．To evaluate the maximum carbon dioxide that trees can absorb.
D．To see the growth rate of these trees.

A．Chad Lake located in the middle of Chad in northern Africa.
B．The water from Chad water can now only be used for irrigation.
C．The area around Chad Lake has suffered from heavy rain lack many decades.
D．Population around the Chad Lake now begins to decrease due to water lack.