Lake Chad,on the Border of the Sahara Desert

Lake Chad,on the border of the Sahara Desert,

A) Is the last surviving deep-water lake in Africa and represents an important and stable water source for Chad, Niger, Nigeria and Cameroon.
B) Is a good analogy to Lake Erie, in that it has undergone extensive rehabilitation after being severely polluted and is now a healthy water source.
C) Was originally a glacier that melted and so the water supply is dwindling.
D) Is a shrinking, shallow-water lake, depleted both by withdrawals for irrigation and by lack of recharge during a multi-decade period of declining rainfall.