If the battery was removed, the energy produced by the battery would not be able to continue its path along the circuit.
According to Raoult's law, Vapor pressure is directly proportional to the mole fraction of the solution. As 1.0 M CaF2 has least moles here, it has lowest vapor pressure.
In short, Your Answer would be Option D
Hope this helps!
The the forth layer known as the thermosphere can reach as high as 2000 degrees Celsius.
