For which direction or directions of the magnetic field will there be zero magnetic force on the proton?

Question

A proton with an initial velocity of magnitude v in the +x direction enters a uniform magnetic field. For which direction or directions of the magnetic field, if any, will there be zero magnetic force on the proton?

+ x
- x
+ y
- y
+ z
- z
Check here if none of the above apply.


I don't know where to start...

Answer 1

+x and -x
force=v X B where X stands for the vector cross product and = 0 when v and B are parallel