By gathering information from past facts
This is True . the reabsorption through the proximal tubule is obligatory 80% whereas water reabsorption through distal tubule is facultative but mostly through collector tubules 15 % ( under the action of aldosteron and antidiuretic hormone).
The answer is c because of science
a)121 million gigatons or 121 million billion metric tons" of carbon).
B)The ocean, with around 38,000 gigatons
c)60 gigatons of carbon
