In a region, steady and uniform electric and magnetic fields are present. These two fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be a

straight line

The charged particle will move along the lines of electric field (and magnetic field). Magnetic field will exert no force as the velocity of particle is parrallel to the magnetic field. The force by electric field will be along the lines of uniform electric field. Hence the particle will move in a straight line.