Hi, I don't get this.

17. A straight current-carrying conductor, OR, is connected to a battery and a variable Bob resistor. OR is enclosed in an evacuated chamber with a fluorescent screen at one end. Fluorescent screen X Chen Chen Bob M R Y Chen Bob Cathode ray Variable resistor Bob Chen Battery A cathode ray enters the chamber directly above @, initially travelling parallel to QR. It passes through the chamber and strikes the fluorescent screen causing a bright spot. Bol Which direction will this spot move towards if the resistance is increased? A. W B. X Bob Chen Bol C. Y D. Z