The answer is d because you are using energy to pull the sled back up, which is mechanical energy
The magnetic force acting on the proton is

where
q is the proton charge
v is its speed
B is the intensity of the magnetic field

is the angle between the direction of v and B; since the proton is moving perpendicular to the magnetic field,

and

, so the force becomes

this force provides the centripetal force that keeps the proton in circular motion:

where the term on the left is the centripetal force, with
m being the mass of the proton
r the radius of its orbit
Re-arranging the previous equation, we can find the radius of the proton's orbit:

And now we can calculate the centripetal acceleration of the proton, which is given by
Answer:
They will run parallel to each other as the none of a straight pole cannot be bent in such a way where one side can turn without the other turning.
They depend on it because this helps them maintain nutirance and survive and reproduce more.
The work done by the electric field in moving a charge is the negative of the potential energy difference between the two locations, which is the product between the magnitude of the charge q and the potential difference

:

The proton charge is

, and the two locations have potential of

and

, therefore the work is