If a charged particle projected in a gravity-free room deflects, then

Since there must be some external force which will cause the deflection of charge particle and it can be both magnetic force or electric force.
Therefore, simultaneously both the fields cannot be zero therefore, option(C).
Option(A) and (B) are saying that there should be electric field compulsory or magnetic field compulsory for deflection which is not true therefore, only option(C).