B, the surface of a flat table.
The x-acis of a trajectory represents its C
Divide
(the distance covered in some period of time)
by
(the time taken to cover the distance).
The quotient is the average speed during that period of time.
Answer:

Explanation:
Given that
Speed ,v= 2 x 10⁵ m/s ( - y direction)
B= 0.6 T (- z direction)
The resultant force on the proton given as

F= m a
For uniform motion acceleration should be zero.
F = 0






Electric filed should be apply in the negative x direction.