Proton in magnetic and electric field

[syhpui2]

Homework Statement

As shown in the figure below, a proton moves in the +x direction with speed v and is immersed in both, a uniform magnetic field, B, oriented in the -z direction, and a uniform electric field, E (not shown in the diagram). What electric field orientation is required in order for the proton to move un-deflected through the combined magnetic and electric field region?
(a) +y direction
(b) -y direction
(c) +z direction

Answer is B.

http://i.imgur.com/1G80T.png

Homework Equations

qE=qVB

The Attempt at a Solution

I used RHR, I get answer A...

 

[Delphi51]

Which way does the B field push on the proton?
Which way should the E field push on it?

 

[syhpui2]

Which way does the B field push on the proton?
Which way should the E field push on it?

Which way does the B field push on the proton? Along x-axis
Which way should the E field push on it? Opposite direction of qvb?