The answer is C.
The only sphere that is entirely made up of gasses (and that surrounds the earth) is the atmosphere. The gasses in the atmosphere are held in place by the gravity of earth.
All river water comes from melted ice from mountains near them, so the time of year to temp. change depicts how much ice is melted into the river banks.
(Site 1 ) Antarctica
(Site 2) Scientists are so interested in the lake because the conditions could resemble those of ice covered oceans to exist on Jupiter's moon called Europa
