Two protons are going up when they enter a magnetic field that points toward you. what happens to the motion of the particles

Force on a proton when they are moving inside the magnetic field is given by

so here while protons are going upwards we can say its direction of velocity is towards +Y and magnetic field is towards us which is along +Z direction so they will have force due to this motion.

As per above equation of force we can have direction of force which is along +X direction.

So here both proton will bend towards +X direction and start moving in curved path.

because growing process had stoped after 4-5 year

a is the best answer your welcome