In a Cathode Ray Tube Electrons Are Initially Travelling Horizontally

Multiple Choice

In a cathode ray tube electrons are initially travelling horizontally at 4 *10⁶ m/s.The horizontal distance electrons would have to travel for a vertical drop of 0.2 mm in vacuum is

A) 400 m.
B) 1500 m.
C) 3.8 km.
D) 25.5 km.