Answer: A.
It has to be A just from common knowldege.
The electric field between two parallel metal plates is given by

where
E is the electric field
V is the voltage across the two plates
d is the separation between the two plates.
In our problem, the voltage is

while the separation between the plates is

, therefore the magnitude of the electric field is
(C)
...........................
If it's not moving at all at the beginning of the 10 seconds, then it falls 490 meters straight down in 10 seconds.
(Note: This is true of all objects on Earth . . . rubber balls, feathers, grains of sand, school buses, battle ships . . . everything. As long as air doesn't hold them back. Anything falling from rest falls 490 meters in the first 10 seconds.)
All elements are balanced. There are 1 Mg, 1 O, 2 Li's and 2 Cl's.