Question

The motion of a charged particle can be used to distinguish between a magnetic field and electricfield in a certain region by firing the charge (1) Parallel to the field(2) From opposite directions in 1 option the charge particle will accelerate (if charge is positive) in the presence of elcectric field and in case 2 it will deacelerate in presence of electric field in presence of magnetic field the particle would be undeflected in both the cases , then why option 1 is incorrect

Answer 1