Answer:
Electrons
Step-by-step explanation
Only charged particles like protons and electrons can create an electric field. Around every proton and electron there is an electric field. Since electric field is proportional to the magnitude of charge, large number of charges will produce a large field.
The large imbalance electron would create a significant electric field
Note: imbalance of electrons would mean that, there are more ( or less) number of electrons present than there are protons