When you want to set an Entity reference field in Views exposed filter, it only allows free text input filter. But i want to have a selection list instead of a free text input.
Just simply go to the field setting page @ admin/structure/types/manage/<content-type>/fields/<field-name> and check the Render Views filters as select list option.
The selection list is now ready in the exposed filter.
Reference: Entity Reference does not offer select list as a views exposed filter, only text field for id number